The songs are available through Island Tunes. (Sorry, not yet on US iTunes.)
Analysis: I just bought these songs. The “Umbrella” cover is spine-chilling, amazing, mesmerizing, mind blowing, jaw dropping, hair standing, I-can’t-believe-I-just-heard-that unbelievably good. Wow, I just love this version and could listen to this song over and over again (I just listened to the song six times in a row). You’ve got to listen to this song on Island Tunes (you can preview it for free, but it’s even better in its entirety)! Amazing.
The “Summertime” song has a cool, pyschedelic vibe to it, very different from the video above. “Up Here” is pretty much what you hear on the video above.