YouTube videos are already lossy. Exporting to WAV does not reconstruct a studio master. It stop stacking another audio MP3 encoding file on top of the first while you work in reaper or premiere.
On our site at home page when you give any video link then for the quality the default one is MP3 is selection. But from there there are other options also from there you can choose the WAV format. When you select then approx size of that file will be shown. Then just click on download and the downloading audio into the WAV format will started. You not needed any DAW plugin or any APK or software installation. When file will be download you will see that file is PCM, So at any player or on any editors you can open this audio file and play it and edit it. For size you can say that a 10 minutes clip in WAV it will be approx 10mb while same clip if it download into MP3 in 192 kbps will be almost one-third of it.
You should use the WAV only when you want to use the audio into your editing purpose to clip a silent from this audio, change speed, lay the audio into the timeline for background as music etc. Use MP3 at 192 kbps for listening purpose.
How to Export WAV
For exporting to WAV format just open website and at home page paste the video link or click on paste button that showing into the box. Click on Get Audio. You will see the all formats list. Choose the WAV (uncompressed) and then click on download button. You will get a much extra size as compare to the MP3 with 320 kbps. Normally its size is five to ten times more on same duration but also it's depends on sample rate that we explain there.
When MP3 is enough
If your purpose of downloading audio is to just listen then you can use the MP3. And if you have a good headphones or earbuds then in MP3 use the 192 or 320 kbps bitrate quality that give more clarity and loudness. Read the bitrate guide.
Licensing still applies
A WAV of a commercial music is still that music. Using it for your own videos or your client videos for as background or foreground music, or for a podcast for that still you required a license. However if the music source is commercially allow by it's company or person then you can use it. For more you can read our terms here.
Editing Tips
Normally in the DAW after import. If the YouTube source is mono speech then you will not get the wide stereo image as because it is in mono tone previously. Import the WAV, set your project sample rate, and edit from there.