A general thing when writing (or changing) wiki-articles:
Make sure images are small, it's better for readability and not all users have broadband connection.
I have to connect via ISDN, there is no other posibility at the moment, and if an article needs minutes to load I just close the tab.
And a bout flash-videos:
I would prefer not to use proprietary formats ( I also use png's instead of gifs therefore and because they are smaller the most times).
A flash video would force the user to have a flash-player installed. That's not html and makes parts of the wiki unusable for people, that don't have and/or don't want to have a flash-player, that means a "normal" (step-by-step-)instruction is still needed.
It's more work to write an instruction, but another advantage is the possibility to print the articles.
I prefer to have documentation on paper not on screen, but that's of course a matter of taste.