Hi all.

I'm a conference technician for a company in the UK. The company runs a menagerie of different combinations of OS and PowerPoint, nowadays mostly Vista and 7 x32 and x64, with PP 2007 and 2010.

We have a lot of problems with people bringing powerpoints filled with videos (some presentations will have one or two, some will have forty or fifty, there have been a couple with more than a hundred embedded videos). I'm going to describe in a list the issues that we have, and then the fixes that we go through in order to correct these seemingly-random occurences.

Videos render a preview frame, but on play present a black screen (this is the major one)
Videos are set to loop and loop with ~1s of black screen between end and start
Videos are set to loop and do not loop on the first few clicks (think starting a manual petrol mower)
Videos play when a machine is not outputting on its second display, but then on connection to a projector either do not play at all (with a black placeholder, or a white placeholder), or play on the output only (the latter issue is less of a problem, just causes a few mini-heart attacks...!)

Videos which have been imported to a W7 x64 machine running PP 2007 are transferred to another machine also running W7 x64/PP2007, and then stop playing. This appears to happen even if both computers apparently have the correct codec (according to G-Spot).

Our most common fixes include:

Changing the extension of a video which doesn't play (say, from .wmv to .avi, or .mpg to .wmv, or .mpg to .wmv, there isn't any particular rhyme or reason to it). Just changing the extension of the video and re-importing it will usually make PowerPoint play it - Why?

Setting an external output to be the primary display device on a computer will occasionally fix videos which wouldn't otherwise play.

My question is, firstly, why the heck does changing the file extension determine whether powerpoint plays a video or not? The container and encoder are still the same, the ONLY thing that's different are three letters at the end of a filename.

Are we doing something wrong to be having such problems with PowerPoint according to the list above, or is it just a really buggy program?

Would love to get some expert advice on this.