Yes. sip2sip.info supports video. As does opensips.org and iptel.org.
However, voxalot doesnt seem to support video themselves or for any external provider you might add in your list.
Correct me if i am wrong, but voxalot does not forward incomming video nor outgoing if you have a provider what supports it?
I tryed to add h263 as a codec on a external provider, wouldnt let me