File exists but VideoCapture fails to open, isOpened() returns False

I have the exact same problem, vid.isOpened() returns false

file exists and opens fine with video player (VLC) but OpenCV doesn’t like it for some reason. I am building for MAC

here is the build information.

General configuration for OpenCV 4.9.0 =====================================
  Version control:               4.9.0

  Extra modules:
    Location (extra):            <INTENTIONALLY_REMOVED>/src/opencv_contrib/modules
    Version control (extra):     4.9.0

    Timestamp:                   2024-01-10T13:48:02Z
    Host:                        <INTENTIONALLY-REMOVED>
    CMake:                       3.27.7
    CMake generator:             Unix Makefiles
    CMake build tool:            /usr/bin/gmake
    Configuration:               Release

  CPU/HW features:
    Baseline:                    SSE SSE2 SSE3
      requested:                 SSE3
    Dispatched code generation:  SSE4_1 SSE4_2 FP16 AVX AVX2 AVX512_SKX
      requested:                 SSE4_1 SSE4_2 AVX FP16 AVX2 AVX512_SKX
      SSE4_1 (16 files):         + SSSE3 SSE4_1
      SSE4_2 (2 files):          + SSSE3 SSE4_1 POPCNT SSE4_2
      FP16 (1 files):            + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 AVX
      AVX (9 files):             + SSSE3 SSE4_1 POPCNT SSE4_2 AVX
      AVX2 (36 files):           + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2
      AVX512_SKX (8 files):      + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2 AVX_512F AVX512_COMMON AVX512_SKX

    Built as dynamic libs?:      YES
    C++ standard:                11
    C++ Compiler:                /usr/bin/clang++  (ver 16.0.6)
    C++ flags (Release):         -fsigned-char -W -Wall -Wreturn-type -Wnon-virtual-dtor -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Winconsistent-missing-override -Wno-delete-non-virtual-dtor -Wno-unnamed-type-template-args -Wno-comment -Wno-deprecated-enum-enum-conversion -Wno-deprecated-anon-enum-enum-conversion -fdiagnostics-show-option -Wno-long-long -pthread -Qunused-arguments -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG  -DNDEBUG
    C++ flags (Debug):           -fsigned-char -W -Wall -Wreturn-type -Wnon-virtual-dtor -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Winconsistent-missing-override -Wno-delete-non-virtual-dtor -Wno-unnamed-type-template-args -Wno-comment -Wno-deprecated-enum-enum-conversion -Wno-deprecated-anon-enum-enum-conversion -fdiagnostics-show-option -Wno-long-long -pthread -Qunused-arguments -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -g  -O0 -DDEBUG -D_DEBUG
    C Compiler:                  /usr/bin/clang
    C flags (Release):           -fsigned-char -W -Wall -Wreturn-type -Wnon-virtual-dtor -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Winconsistent-missing-override -Wno-delete-non-virtual-dtor -Wno-unnamed-type-template-args -Wno-comment -Wno-deprecated-enum-enum-conversion -Wno-deprecated-anon-enum-enum-conversion -fdiagnostics-show-option -Wno-long-long -pthread -Qunused-arguments -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG  -DNDEBUG
    C flags (Debug):             -fsigned-char -W -Wall -Wreturn-type -Wnon-virtual-dtor -Waddress -Wsequence-point -Wformat -Wformat-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Winconsistent-missing-override -Wno-delete-non-virtual-dtor -Wno-unnamed-type-template-args -Wno-comment -Wno-deprecated-enum-enum-conversion -Wno-deprecated-anon-enum-enum-conversion -fdiagnostics-show-option -Wno-long-long -pthread -Qunused-arguments -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -g  -O0 -DDEBUG -D_DEBUG
    Linker flags (Release):      -Wl,--gc-sections -Wl,--as-needed -Wl,--no-undefined  
    Linker flags (Debug):        -Wl,--gc-sections -Wl,--as-needed -Wl,--no-undefined  
    ccache:                      YES
    Precompiled headers:         NO
    Extra dependencies:          dl m pthread rt
    3rdparty dependencies:

  OpenCV modules:
    To be built:                 alphamat aruco bgsegm bioinspired calib3d ccalib core datasets dnn dnn_objdetect dnn_superres dpm face features2d flann freetype fuzzy hfs highgui img_hash imgcodecs imgproc intensity_transform java line_descriptor mcc ml objdetect optflow phase_unwrapping photo plot python3 quality rapid reg rgbd saliency shape stereo stitching structured_light superres surface_matching text tracking ts video videoio videostab wechat_qrcode xfeatures2d ximgproc xobjdetect xphoto
    Disabled:                    gapi hdf world
    Disabled by dependency:      -
    Unavailable:                 cannops cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev cvv julia matlab ovis python2 sfm viz
    Applications:                tests apps
    Documentation:               NO
    Non-free algorithms:         NO

  GUI:                           NONE
    VTK support:                 NO

  Media I/O: 
    ZLib:                        /usr/lib/x86_64-linux-gnu/ (ver 1.3)
    JPEG:                        /usr/lib/x86_64-linux-gnu/ (ver 62)
    WEBP:                        /usr/lib/x86_64-linux-gnu/ (ver encoder: 0x020f)
    PNG:                         /usr/lib/x86_64-linux-gnu/ (ver 1.6.40)
    TIFF:                        /usr/lib/x86_64-linux-gnu/ (ver 42 / 4.5.1)
    JPEG 2000:                   OpenJPEG (ver 2.5.0)
    HDR:                         YES
    SUNRASTER:                   YES
    PXM:                         YES
    PFM:                         YES

  Video I/O:
    DC1394:                      YES (2.2.6)
    FFMPEG:                      YES
      avcodec:                   YES (60.3.100)
      avformat:                  YES (60.3.100)
      avutil:                    YES (58.2.100)
      swscale:                   YES (7.1.100)
      avresample:                NO
    v4l/v4l2:                    YES (linux/videodev2.h)

  Parallel framework:            pthreads

  Trace:                         YES (with Intel ITT)

  Other third-party libraries:
    VA:                          NO
    Lapack:                      YES (/usr/lib/x86_64-linux-gnu/ /usr/lib/x86_64-linux-gnu/ /usr/lib/x86_64-linux-gnu/
    Eigen:                       YES (ver 3.4.0)
    Custom HAL:                  NO

  Python 3:
    Interpreter:                 /usr/bin/python3 (ver 3.11.6)
    Libraries:                   /usr/lib/x86_64-linux-gnu/ (ver 3.11.6)
    numpy:                       /usr/lib/python3/dist-packages/numpy/core/include (ver 1.24.2)
    install path:                lib/python3.11/dist-packages/cv2/python-3.11

  Python (for build):            /usr/bin/python3

    ant:                         /bin/ant (ver 1.10.14)
    Java:                        NO
    JNI:                         /usr/lib/jvm/default-java/include /usr/lib/jvm/default-java/include/linux /usr/lib/jvm/default-java/include
    Java wrappers:               YES (ANT)
    Java tests:                  YES

  Install to:                    /usr/local


does the output agree with your expectation?