BBM 7 has been a super welcome addition to the OS with its native BBM Voice capabilities. One of the logical rumors regarding BBM and BlackBerry 10 is that these capabilities would be extended into video calls as well.
The thing with BBM Voice on OS 7 is that calls are restricted to over WiFi only, and it seems with BlackBerry 10 this may be changing. According to this leaked screenshot, BBM calls (encompassing both video and voice calls) will be able to be used over the user's mobile network on BlackBerry 10. The setting will be able to be turned on or off like most options on BBM are right now.
How AT&T, and other carriers that like to clamp down on video chatting and other "special uses" of a user's data, feel about this option on BlackBerry 10's BBM remains to be seen. It wouldn't surprise me if they tried to block this specific option somehow, but at least with the units that are out there, this is definitely possible right now.