Before initiating the download, basic due diligence is required to ensure the link is legitimate and safe.
ffmpeg -v error -i downloaded_video.mp4 -f null - 2> error.log
For container validation (MP4):
ffmpeg -i downloaded_video.mp4 -c copy -f null -
A common issue with large video downloads from file hosts is an incomplete transfer, resulting in a file that stops playing halfway through.