Actually, no one has asked this question before, so thanks for being original!
According to the liner notes of the Love Your Ground EP, the background vocals were provided by “LM Dog and Ashley Lovett.” As far as who is playing drums is concerned, I have no idea! One could assume that they recorded the song with Marcus on drumset, but, as you said, the one video available of the boys performing it live is too dark to see anyone other than Marcus on guitar.
Luckily for us, someone’s camera flash illuminated the boys in that video long enough for me to get this screen shot:
I’m sad to say we can’t see who’s playing drums (actually, I don’t even see drums on that little stage!), but it’s still interesting to see how far the boys have come since 2008. For your enjoyment, I’ll post the video momentarily.
Thank you again for your question! Let me know if you have any others!