I find myself reusing a handful of FFmpeg commands. Here's what I use most often.

Extract LPCM Audio Track

Extracts an audio track from a fully muxed input file.

ffmpeg -i stream_file.m2ts -map 0:a:0 audio.wav
Extract a Video Track

Extracts a video track from a muxed input file.

ffmpeg -i stream_file.m2ts -c copy -an vid_only.mp4