How Much Perceived Value Does Video Have?

I note that a lot of people recommend adding videos to their product, or making the product a video as opposed to an eBook. The typical reason given is that video has a higher perceived value than just text.

Note that people generally say a higher perceived value rather than a higher actual value.

Establishing an actual value would naturally depend on the product, but when we're talking about a perceived value, is there any hint or indication as to what that might be? Does a video product have, say, a 10% greater perceived value than text? 20%? 30%?

I have an eBook that I am finalizing, and I am wondering if it would be worth the effort to create a set of videos to go along with it. My target price for the eBook is $37. I haven't gotten any feedback from my test readers yet, but I think that $37 is a good value for the eBook as planned. So, I'm wondering what value might be added if I were to do videos? Could I charge more, or is it something that would help to increase conversions?

The videos wouldn't contain any additional information beyond what is in the eBook. The benefit would be to those that want to watch or see something because maybe it's easier for them to learn by seeing something being done rather than reading about it. Where step-by-step instructions are needed, I think I've done a thorough job of covering that in the eBook, so the video would simply show that.

Or, do I release the eBook as planned, and maybe add videos later depending on sales? I'd really like to get this eBook done and out the door; if I add videos, I'm guessing that may add an additional month to finalize.