None of the videos are loading for me.
This is known and won’t be fixed. The site owners accidentally lost them when closing the site and making a read-only copy. There is no public intent from OpenAI as far as I know to fix this. Instead, all publicly shared coding effort is going into Gym and Universe.
This is a shame perhaps, but maybe a reasonable decision for priorities. Apparently the interactive gym site was not getting enough attention to be considered worthwhile (I don’t have any figures or evidence either way, just repeating what I read on the log where this was discussed).