Jules,

In regards to the first item you've noted - you may want to try enabling the exact settings your work computer uses.
You've mentioned that changing the resolution didn't solve the problem; however have you tried using the resolution your work computer uses? In order for this fix to work, make sure that the window size is the same as your work's computer once the resolution matches. If this doesn't solve the issue, perhaps I can help write a tool for you that outputs the size of all the videos you're using. This may make it a bit easier to work with if you do indeed have to use the last option (manually adding in the video size).

In regards to the video loading issue - I believe the delay is due to the architecture Windows Vista uses. Videos should load faster in Windows Vista due to the DirectX 9 / DirectX 10 libraries being used to render the video. I'm not sure if anything can currently be done to increase the speed at which videos are loaded.

The 2010 copy of ML should be able to load videos much faster.

Regards,
Trevor