the browser let's you set the download location but it will not be site specific.
however, i assume if you're grabbing yt videos, then you are using some kind of plugin. the plugin should allow you to say where those files go. i don't use chrome so i guess if it allows for downloading yt videos directly without a plug-in, then you'll need something else to direct those specific files where you want.
you could use a different browser just for grabbing those videos. would allow for specific location and not mess with default location of other browser.
chrome has a portable version that can run alongside your pc's installation allowing different settings for each
https://portableapps.com/apps/internet/google_chrome_portable...