Sorry again, problem is that I'm looking through multiple theme files. Here's the issue, I was looking at my Mojo theme that I had modified, but I forgot that I had modified the xml also.
I had to go back and actually look at the original xml's to see which images to address. Most of the services use the same ..bg.png file which is "image/mediafly_encoding_bg.png", so it uses that image from the main image folder and not the subfolders.
To modify though for youtube, open the xml "inc_yt_widgets.xml" and modify that image to the one you want. I would suggest placing the image in the youtube folder then change the line:
and change the name of the image to match.
For the weather, this one I'm not to sure of because there seems to have been some changes to it since the last time I did any mods to it, but you can try "image/accuweather/accuweather_encoding_bg.png", I will try to confirm that this is the correct image when I get a chance. If it's not then I will attempt to find the correct one and post it.
For all other services though (if you decided to change them as well) they should almost all be the "image/mediafly_encoding_bg.png", but to change each individual one to something different you will have to find the corrosponding xml and change it.