What’s the compression codec you are using? Also, make sure it’s an .MOV file for troubleshooting and that it’s using a supported compression codec for your machine. Please note, the .MP4 and .MOV file types are essentially file containers, the codec is how the file is compressed and decompressed to be read.
That’s interesting, because we should support H264 just fine. Can you send me the file for testing to maryp at borisfx dot com? I will share it with the team and see what the difference is.