If the file shows a brand like "isom," use mp4box to change the brand to mp42 . To make this guide better, please tell me:
Are you trying to (e.g., in Premiere Pro) or just play the video? 5 6251481326331890651 mp4
Once I know this, I can tell you exactly which step to take. If the file shows a brand like "isom,"
What or symptom (e.g., green screen, no audio) are you seeing? which increases compatibility.
Use a tool like Handbrake to re-encode the file to a standard H.264 format, which increases compatibility.