my experience with a sony hdr-cx250e and BBB is this:
connect the cx250e to computer by a usb video/audio caputure (like hauppage or roxio) and install the drivers.
After this you can see the usb video/audio capture device like video and audio source in your flash plugin.
I don't know why but, for me, only work with windows Vista.
If i try with Windows 7 the system tell me the camera7device is already open by another application ... but there is no other application open
Of course the quality is not the best, but for my really limit upload speed is enought.
Michele