“unable to load video. An error occurred while loading a higher quality version of this video” ?

Your post does not provide much detail, but it suggests you may be trying to view an unsupported video format. Where are you getting the videos which do not work?

Can you make your own video recordings for test, and view them correctly? Can you view other videos correctly?

If the problem video is requiring you to download additional codecs from a non-Apple source I recommend you should be very cautious, because this is a frequent method for bad operators to get malware installed onto mobile devices (the so called video support app is really a trojan).