Here’s how to get around it. Head to http://hola.org and download the Hola Unblocker. It’s available for multiple platforms, including as an add-in for Firefox and Chrome.
The Big Secret is that Animated Twitter avatars only seem to work properly in certain sizes: 48px, 96px, 128px, 192px, and 384px! If you upload another size, it either won’t work at all, or it’ll get mangled!
Gramblr.com will do the work… Download the application and don’t forget to add captions!