Do online students deserve video content?
First of all, what students do or do not "deserve" is more of a moral/philosophical question than an academic question. However, I will attempt to respond to your situation in a way that is academically practical.

Students who are attending the in-person classes are getting a live, visual, possibly interactive version of the content, but online students are getting something different. Given that you mentioned online students asking for more visual media content, but no in-class students requesting an extra explanatory text, one might reasonably infer that the visual is more highly demanded. Also, you didn't explicitly say that the explanatory text is a transcript of the lecture or a copy of your lecture notes, so I'm going to assume it is not simply an identical typed version of what is said out loud. If students are taking the same course with the same assignments, syllabus, and expectations, it is reasonable for them to expect to get as close to identical materials as possible.

However, I don't think they are expecting a scripted/staged/performed video either. In most of my classes, the professor records a screencaptured video of the projector and/or a video of the lecture and posts it to the class' online site. That way, if you miss class, you can see what you missed as it played out. These videos aren't particularly high quality or effort, but they allow students to watch lectures even when they physically can't. Most students I know taking online classes aren't doing so because they prefer the format, they're doing so because they can't physically attend the class at the offered time but still want/need to take the class. Offering lecture videos helps to equalize the material available to both online and in class students.

Before you take any action, I recommend:


Checking to see if your university has a policy on recording lectures/seminars
Check to see how expensive it would be to start recording lectures
Survey your online students to ask if lecture videos would be beneficial. (If you find out it's not expensive, I would skip this step based on the feedback you've already received).