Hi Loadman,
Just tried the latest beta and the gifs seem to playing properly now. However there are a few more bugs now I think.
Firstly the new beta seems to blur the gif animations, I've attached an image below showing the difference between mala 1735 and 1739 to show the problem.

Second new problem is that the gif now shows as a solid black box before it begins playing now. It's only for a second but it just takes the shine off a bit and it doesn't happen in 173.5
The next problem is related to the screensaver, after exiting the screensaver the gif doesn't seem to be returned to the exact same size as set in the layout so you get a black line either to the right or to the bottom of the gif (1735 puts a line at the right in my case and 1739 puts a line at the bottom.) I think it's related to the size of the video window changing as you get the same black borders if the window isn't scaled to the same ratio as the actual gif.
The image below shows the problem, the black line is only 1 pixel high and only shows after the screensaver has been active. The bottom of the gif I'm using is just underneath the joysticks and is where the black line is appearing.

Finally the setting for the video2 window size don't seem to be very accurate, the layout is fixed size 1024x768 and the gif was designed specifically for that resolution but the video2 window size doesn't match what is entered in the layout (or maybe the video isn't matching the window). It doesn't seem to affect all sizes of Gifs though as after some tests some render at exactly the size entered but I haven't managed to narrow it down to exactly what sizes/ratios cause the problem so I'll investigate further to give you more solid information to work on.
Sorry for the extra long post, hope I didn't ramble too much. I'll provide more information as I find it.
Thanks for all the hard work.