That is the one thing I’ve never done. I will try it and get back to you.
As a client, I’ve also never seen someone with a video in their profile, or don’t understand where it appears in the results section.
My intuition tells me that Upwork wouldn’t put the option to add a video if they didn’t think it was useful. Also, if they think it’s useful, I can’t imagine it doesn’t play some factor in their algorithm. So my intuition tells me that it’s probably worth having, even if it’s a placeholder.