Jitsi uses about 5.5Mbps per connected Chrome user. This math doesn't line up, but if Jitsi isn't transporting the 720p video 10Mbps might work for 6 users.
1:1 video uses P2P and doesn't require video going through the Jitsi bridge.
Tbf, the bitrate depends entirely on the res constraints you've specified. We see 1Mbps when requesting 854x480, which seems to be quite a reasonable resolution when on a multiway conference.
