Yes. XMPP has a solid core with a lot of optional extensions, see https://xmpp.org/extensions/index.html for the full list of available extensions.
To support a specific feature all involved entities (server and/or client(s)) must support the XEP extension for this feature. Implementing the support for a client requires some time so we can’t simply support everything.
And sending/receiving videos is possible with Kontalk, is it not working for you?