Hello,
Thank you for contacting NCH Software.
Suggest you do look around, there are a few people trying to extract audio from YT .flv’s
1 – Use FlashLynx to rip the .flv from YT
2 – Dump the file into WavePad and save as an .mp3
Note – Your microphone noise is coming from the microphone connected to your PC, disconnect, or disable it in the future.
Cheers
M