No BetaSP can go directly from an HDV camera because it’s not an NTSC Standard definition signal. I’m sure you’re buddy could record the standard DV signal from the Sony cam just as he could from the HVX going via RCA or S-Video outputs. As for the quality being better than a Sony DSR250- kind of a subjective question. With the HVX you would would get 24p, not to mention increased color fidelity over the DVCAM camera, but the Sony does have access to potentially better lenses- so depends on your definition of what’s better.
Noah