My understanding of "Max Bitrate" is that is can be helpful IF your source video had a high color depth, such as 10-bit or 12-bit video, or a lot of graphics. For regular video that started as 8-bit, then Max Depth will not help. Rather, you will want to check the box for "Max Render Quality" as this helps with the downscale quality from HD to SD.
As for 2-Pass VBR encoding, the first pass analyzes the content of the video for motion and complexity, so that it can allocate the bitrates for various scenes accordingly when it does the actual encode on the second pass. This takes longer, but should yield better results. It encodes more efficiently to squeeze the most quality possible out of the video.
Thanks
Jeff Pulera
Safe Harbor Computers
