It's a tricky slope. Sure, in a perfect storm, we'd all have decent promotional video of our selves or our band. Fact is not everyone does or will pay for this.
Unless it's a startup, the band really should have some video clips that they use for their own promotion. There's really no reason that they couldn't put together a rehearsal video, but if you don't have a drummer for example, you're not gong to present well. Bit of a catch 22.
And for personal video, it's a matter of did I get lucky enough to get any feature time in some random person's band video? Usually not for me. I put together a video clip of some of my previous band's shows so I have something that shows me playing with a band in a live setting. It's really not very good, but when a band insists on a video sample, I have something to send. The videos themselves are fairly crappy and my presence in them is even worse (there's a couple clips where I'm hidden behind a PA speaker.) It's really not even worth the bother, because I've never been invited to an audition when they required a video. I'm not a photogenic type of person; I'm not quick to smile and it looks absolutely fake when I have to pretend to look happy. The idea of intentionally posing in front of a camera to promote myself just pains me and I never come off well.
For me:
- Let me come jam with you typically = you won't be sorry. You may select someone else, I'll at least be considered.
- Sending a video = don't waste my time. (kind of like on line dating

)
One of my bands is looking for a KB player. We had interest from someone who had some videos of his band and they were not great. It wasn't awful, but it was basically a 1/2 step above garage band quality. We didn't ask for video, I just went snooping. In this case, the guy already has a strike against him before he even shows up. Maybe it was a couple of bad gigs, but it is certainly bad judgement to have this material out there for people to find.
So promotional videos are a bit like harmonies: bad is worse than none.
When I'm considering auditioning for a band, I do as much research as I can to see what their product is but unless I just get creep vibes from the communication process, I won't not go just because they have no video presence. Part of the fun of the music business is the discovery of new people and personalities. It's also part of the hell.