If you are having difficulty uploading a custom exercise on YouTube it is likely the video URL needs to be changed due to the video not being supported.
Any videos under 60 seconds will not be accepted by YouTube due to the videos now being classified as ’shorts’.
If your video is ‘short’ the URL will display similar to this- https://www.youtube.com/shorts/XXXXX(each link will have its own unique code here)
You will need to change the link to https://www.youtube.com/watch?v=XXXX
All we have done here is replace /shorts/ to /watch?v= before you add the video ID.