Also re-encoding a low bit rate file will also look worse when encoded at a low bit rate, and 2 mbps is a very low bit rate for a 1920X800 video. You should always try to start with the best quality source you can get.
For example if I do a recording of a film program I will set the bit rate to constant at the highest setting to capture the file with the best quality, and my source is almost always 1080i at 29.97 fps. I then do any editing I need using VideoRedo and save the file in the same format as it was recorded. I then re-encode the 1080i file into 1080P AT 23.976 and make any changes to color or other settings, like if the file was wide screen with black bars on top and bottom and there was a logo ID inserted in the black bar area I can re-insert black bars again and remove the logo. I set the encode to be either a 2 pass encode if I want to end with a certain file size like for a DVD or Blu-Ray disk or I will do a 1 pass "constant quality" encode to save encode time but with an unknown final file size.
Hope this is not to confusing, it is difficult to explain but pretty easy to do once you have been doing it for a few years.