First, you’ll need to browse to the video you’d like to repeat. Then, you will edit the URL in the address bar, in the manner shown above below.
Note: The video you choose doesn’t matter, the URL below is one we’ve chosen as an example to illustrate the process.
example : https://www.youtube.com/watch?v=86BX_0av_cg Then, you will edit the URL in the address bar youtuberepeat.com/watch?v=86BX_0av_cg
1. Erase everything in front of youtube. In the example above, “https://www” is the section that is deleted.
2. After youtube, type repeat to make the URL look like the one shown below, and then press Enter.
3. After pressing Enter, your browser will open a page with a URL similar to the one shown here: http://www.listenonrepeat.com/watch/?v=dD40VXFkusw
4. This page will repeat your video until it is closed.
Tip: This page also has a counter to let you know how many times the video has been repeated.
Source from : https://www.computerhope.com/tips/tip196.htm