I have seen some tables with a telescoping center floor pedestal (originally meant for boats, I think). Check this AUD $350 (USD $270) baby out:
https://youtu.be/tXfffo8TN3s. Also has a neat dual axis sliding top that rotates as well. If I were to make an RV office nook from a dinette, I might use this to switch from dinette mode, to desk with long edge along the wall, and a chair in the aisle.
https://www.rvpartsexpress.com.au/index ... ystem.html

- Mapa telescopic
Or a USD $70 standalone hinged stand like this one:
https://youtu.be/Zu1QpNzKtFY. Although it has much less leg room, I like the way the whole table can be moved.
http://www.factoryrvsurplus.com/product ... ct_id=2546

- rvsurplus hinge
Got any pictures of the gizmo you saw on TV? Oh wait, did you mean this?
https://youtu.be/K8tvZdb1dVY

- dream dinette
If so, it's called the "Dream Dinette" mechanism and I have a link to the maker somewhere. Ah, here. They used to have a photo of it but not now.
https://casshudson.com/12-specialty-rv-components.
It's similar to the tech used in heavy sewing machine cabinet lifts. In fact, I almost used one of those lifts, but it didn't quite go the necessary vertical distance.
Here's a link to someone's DIY installation:
http://www.irv2.com/forums/f258/weekend ... 87412.html. Says they paid $150 plus shipping. Here's the installation instructions PDF:
https://comnet2.newmarcorp.com/instance ... 104265.pdf
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Coincidentally, for the past six months I have been very slowly putting together a power wall-mounted dinette table slide, with no leg interference at all.
I'm using a restaurant cantilever tabletop wall mount, attached via ball bearing slides to two vertical linear guide rails on the wall, and raised/lowered by a 12v linear actuator with a 16" stroke length. (From 13" above the floor in bed mode, to 29" high in table mode.)
I'm also experimenting with using an automobile cable power window mechanism, which would work far faster... changing position in a few seconds versus the actuator's slower half minute. Might have to come up with a lighter weight tabletop though.
The idea is to make it as simple as flicking a switch to raise/lower the dinette table top into position.