Well, I just compared the number of cells, and I get:
Oblivion - around 4800 cells
Skyrim - around 3900 cells
Now I don't wanna start a panic, so I'll add that 1) we don't know how comparable the sizes of the cells are and 2) my number for Skyrim is a very rough estimation, possibly with faulty data.
What I did was that I took the Skyrim map seen in the videos and looked at how big one cell is (I tried to make a good estimation by counting several cells and dividing their pixels by their number). Then I made a second transparent layer and blackened the Skyrim area on the map (everything within the actual borders of Skyrim), and let GIMP give me the number of black pixels in that layer. Then I divided that by the square of my estimated cell size.
Same procedure for Cyrodiil.
edit: Wait, after rechecking I get 4800 cells for Cyrodiil. Now I'm confused. Just to be on the safe side, I switched to that number and also changed the word "hype" to "panic"
(Yes, I just re-checked both values, they seem to be correct now. Although I do get an uncertainty of around +-100 cells.)