Hello,

Youtube video links in quiz questsions shows and error in editing mode but they work in preview and for students.

Tested with 4.1 & 4.3 at https://sandbox.moodledemo.net

error.mp4

Steps to repeat:

1. Add true/false question
2. Use "add multimedia" > video > button and add for example https://www.youtube.com/watch?v=Ck6S5c0Zv4c
3. notice the error message.
4. save
5. check preview and notice that video works
6. edit the question and notice the error