Preferred amount/length for mpeg galleries?

[Garou]

4 mpegs / 20 second/ 2 mb (1.5 mb sometimes) - most acceptable
4 mpegs / 15 sec / 2 mb (1.5mb sometimes) - good
3 mpegs / 20 secs / 2 mb (1.5 mb sometimes) - some will decline that
wmv is declined on some big guys.
Matching thumbs is a must (use the first frame if its quality is good enough. Otherwise use the first hq frame in the clip)