my audio is getting thrown off slightly. I wanted to add a few seconds of black before a video, and matched up the video resolution and audio rate, but I did see 3 differences between the files in Mpeg2Schnitt info window.

First clip says:
Profile/Level: Main/Main progressive sequence.
DC precision: 8
Top field first: No.

Second clip says:
Profile/Level: Main/Main
DC Precision: 10
Top field first: Yes

Does any of this matter?