They use IPFS as a backend. People can help by running their own IPFS node and caching the videos to their node. This should increase the robustness of the file. Currently they seem to rely on public gateways for serving videos to the general public which can be unreliable since they don't control them.
I try to watch each video through my node so that it can help others.
Edit: For example only 3 machines hold the source video and 4 hold the 420p as of right now. I'm one of each of those.