How do I close the sidebar without losing my youtube video

I cannot figure out how to close the bar…I have to close everything down and start the video again from scratch…I am new so I’m sure there is an obvious answer but any help would be appreciated…Much Thanks…

If you play a video on a lesson page, it will be interrupted when you select a word and replaced with blue or yellow popup. However, if you just click on the “Video” option at the top, the video will re-appear back on the right and continue from the place it was interrupted at.