Hello @Paigeywat
If the videos work on a browser and were working on your tablet until recently, it is likely your device. You should try clearing the cache and cookies first. Either on your browser or the app:
In Chrome
On your computer, open Chrome.
At the top right, click the three dots
Click settings and then Clear browsing data.
At the top, choose a time range. To delete everything, select All time. I suggest at least 4 weeks
Next to "Cookies and other site data" and "Cached images and files," check the boxes.
Click Clear data.
If you are using the Canvas app currently we also recommend doing the same thing:
https://community.canvaslms.com/t5/Canvas-Student-iOS-Guide/What-Student-app-options-can-I-manage-fr...