No looping means 6 second content will not have any impact on the viewer. Maybe producing a 5 minute video and a 6 second video needs different skills.
The solution seems easy: replicate your 6 seconds clip 50 times and you'll have a 5 minutes video to upload to youtube.
Instagram videos loop
Don't get the downvote. Seems like it would be constructive to discuss why they didn't succeed on youtube, are there workarounds to whatever to platform difference are, etc.
Youtube can be a nasty place. Take a look at the comment section of pretty much any video with a black person in it.
Could the most successful people on Twitter have the same success on Medium?