I need some help understanding bitrates...

[pwhyles]

I've read loads about this but I just don't seem to be able to understand...

I have a file that, when imported into Nero has this information:
Length 21m 23s; PAL; 16.9; Quality: Custom (8000 kbit/s); 720x576 (CCIR-601 D1); Progressive; MPEG-2; Stereo

and GSpot says:
Length 21m 24s; PAL; 16.9; Qf 0.627 (6500 kbps); 720x576; sys Bitrate: 2680 kb/s VBR ...

It's the same file! So how come the bitrate variances?

I processed (exported with lower bitrates to that it reduced the files size) and it did this but then I ended up with GSpot reporting:
Length 21m 23s; ... Qf 0.927 (9610 kbps); ... sys Bitrate: 10080 kb/s VBR (!!!!!)

and the settings I used in Nero were something around 3000 kbps ...

Obviously it's me but what... ?

Baffaled.

[Baldrick]

They doesn't show correct information for mpeg2 video. Use the bitrate viewer program or calculate the bitrate yourself or using a bitrate calculator.