I remember when I first heard that Ernest was in commercials, I had wondered if he originated in his movies or saturday morning series or somewhere else. Then I was watching Ernest Goes to Camp with somebody and during the scene where Ernest told a story about Vern I was told that Ernest was created for commercials and that Vern was part of them (by that time I knew that the saturday morning show was called "Hey Vern It's Ernest" but didn't know that Vern was meant to be a character).
And then I got a video movie guide and noticed an entry on "Ernest Film Festival", which mentioned that it contained "Ernest and Vern" commercials but was a bit more confused because Jim Varney was the only actor listed for it. I wondered if maybe Varney also played Vern or something, but was also confused because Vern wasn't in the movies (at the time I didn't really notice the scene where Ernest visited Vern in Ernest Saves Christmas). I eventually saw a copy of "Ernest Film Festival" at a video store (though I never rented it) and wondered why only Ernest was on the packaging but not Vern.
When I first saw Ernest Rides Again I think I started tog et the gist of who Vern was... That movie ended with Ernest talking to Vern about his next movie, though I think I might have still been confused about it. A few years later I got a book called Total TV and looked in the entry on Hey Vern It's Ernest and the book said that "Vern" was the camera. So for awhile I thoguht that meant that he wasn't an actual character (not thinking that it meant we saw from Vern's point of view). The next time I saw Ernest Saves Christmas I finally noticed that scene of him visiting Vern, and thought he was visiting a camera, with no acknowledgement of how weird that would have been.
Watching the "Hey vern It's Ernest" opening, I think it's a bit weird that the credits for a saturday mornign series listed ALL of the cast (and the writers). Since it was a childrens series I would have expected the cast credits to have been in the end credits (with maybe Jim Varney being the only actor listed in the opening).
Recently James Wolfe of The Angry Video Game Nerd fame did a review of Ernest Scared Stupid. In contrast to The Nostalgia Critic Wolfe actually gave the film a positive review (though when Wolfe reviews movies they are usually positive, unless it's a rare isntance where he reviews a movie in character).
http://www.cinemassacre.com/2010/10/27/ernest-scared-stupid/