I hardly ever come across mash ups of songs that are actual covers that I really like but I've come across a few lately that are worth sharing and here they are with links to the Youtube videos.
Blank Space/Style by Louisa Wendorff
This one is super popular and Taylor Swift herself tweeted it, so if you haven't seen it yet, you need to.
Cool kids/riptide by Less is More and The Queen and King
Home/Dirty Paws by the Gardiner Sisters
Love Story/Viva la Vida by Tanner Townsend
This is a little different than the others and there aren't vocals but it's awesome and I feel like I could play it in the background of my life forever and always feel good.
We Can't Stop/Price Tag by Megan and Jaclyn Davies
Taylor Swift 1989 by Sam Tsui and Kurt Schneider
This is every song on Taylor Swift's 1989 album and it's incredible and so impressive.