Oh thank god I had to beat the game but the bridge person wasn't there because I dragon attacked ad she ran off or something so when I go to the main quest on getting the elder scroll I couldn't get inside which meant I couldn't beat the game
I used this glitch in the Waking Nightmare quest so I wouldn't have to use Vaermina's Torpor and could keep it instead. Not that keeping it really does any good, but it's part of my large collection of items now lolz
I got mine in the Jarl's house in Riften, but you can get them in most high end residences. I think Dragonreach has one too. It's possible with any size plate but it's much more difficult with the small ones, IMO.
I got my plate off the table of in the Jarl's house in Whiterun. But it took me a long time to get through that door with it. I tried it on another door to the lift in the quest to get the Blood scroll but i gave up after a while in frustration.
It's all a matter of how you hold it and the timing. You have to keep the oval with the two ends vertical. The timing is kinda touchy too. Try dropping it as you run through it.