I've had tonnes of copyright claims, sometimes 10 for the same video. I'll tweak it, re-upload and pray the Powers that Be allow it. I wouldn't worry about being banned from YouTube altogether unless you're doing something really stupid and brazen that definitely isn't fair use.
Anyway, more importantly, every time YouTube has a problem with a video they narrow it down to an exact time frame e.g. 33.05 - 33.37 so you can see precisely what they're rejecting. How come they haven't told you this? If you look in your creator studio panel you should be able to find out.
With Amiga demos you can almost guarantee it's because the author sampled a copyright protected track and you're playing too much of it to pass the fair use allowance. I'd be amazed if it has anything to do with the demo presentation itself.
If there's a track you suspect might be the culprit you can check here...
https://www.youtube.com/music_policies
...to confirm its copyright status.
I don't think I'd bother contesting anything unless you know for a fact you created the video and the audio yourself, so they have no leg to stand on. Otherwise just adapt your work, try again and move on. Fair use is decided by the copyright holder in each case so our opinion doesn't count for anything.
Just noticed that the Hardwired demo samples Mike Oldfield's Tubular Bells (you know, the Exorcist theme) and we don't have permission to use it on YouTube.