Embedding (Youtube/Vimeo) Videos on a Raspberry Pi

I'm currently working with Raspberry Pi 3's to show webpages from our server, on site.
In this case, on site means about a 100 remote locations like grade schools, where we can't just walk in and update stuff (so making a site offline is a no-go, working with serviceworkers to cache is okay).

My problem is as followed:
When I try to show videos and/or images on the pages, the raspberry eventually crashes. Because the remote locations don't always have working internet and we do need to show something, we can't rely on refreshing every page.

We've tried both YouTube and Vimeo as video providers, but both crash eventually.

Can someone help or suggest some options?