A few things for you to try if you want. I really think the skinny default windows fonts look ugly to me compared to slightly thicker smooth fonts but every one has their own opinion. You will need to turn off anti-aliasing for your fonts but I think it looks really ugly and you will need to pay with the font sizes and such.
Open up the he control center. (on a default install this would be the monitor looking icon with gears in the middle next to the home icon or the picture of a house on the task bar.)
Expand the "Appearance & Themes" section and select fonts. You will now see several settings for fonts, much more than in windows from the properties of the desktop at least and I never go any further than that in windows.
Try out these settings and see how you like them, I think once you set these you will be ready to futz around on your own after that.
Set to the following:
General: Tahoma 10 "regular"
Fixed width: Courier New 10 "regular" (this setting will allow you to use the MS fonts in FF)
Toolbar: Trebuchet MS 12 "regular"
Menu: Tahoma 10 "regular"
Window Title: Trebuchet MS 10 "Bold"
Taskbar: Tahoma 8 "regular
Desktop: Tahoma 10 "regular"
Set anti-aliasing o slight
FF ( Edit --> prefrences instead of tools options in windows)
Select the "Content" tab
Change the default to "Times New Roman" from "Times"
Select advanced and change
Serif to "Times New Roman"
Sans-serif to "Arial"
Monospace to "Courier New"
Anything else you do or don't like is up to you know. You have enough info to be dangerous with your fonts.
As to the youtube problem via a VM I did not have any problems with that video. It sounds the same in either system for me. You may need to play with your sound settings.