No.
Your capture file is
- compressed MPEG video, with a high bitrate
- compressed MPEG audio.
MainConcept converts the video to:
- compressed MPEG video, with best bitrate and resolution for the kind of DVD you specifically are trying to make, meaning 3 hours on a single disc
- MC is better than WinTV at these resolutions and bitrates, so your quality is much better by using this extra step, it's sharper and has less noise
- it turns the audio into an uncompressed WAV.
Look at your video file that was encoded.
- Is it an MPV or an M2V file?
- What is the file size according to Windows?
Let's get past this part first, worry about audio next.