...They could have had a 3D sketch of Freddie singing along with the band for example...
think of the time Made In Heaven came out (1995), now think of all the big-budget movies from that time (i cant think of any right now maybe waterworld?) and think of the special effects from those movies, all shitty, or not computer generated, and cgi in 1995 costs alot more than cgi in 2005 does. So for a cg Freddie to be singing along with the band, it'd be a lotta lotta money (like 250,000+) for a 4 minute music video.