Amazon has given its Instant Videos app for iOS a huge boost, and just in time for the weekend. First up: you can now finally watch movies and shows in HD on your devices. No more putting up with standard definition if crisp, clear visuals are essential to your enjoyment. You'll likely still find yourself switching to lower resolution every now and then, though, especially if you're using cellular data. Yep, that's the other big upgrade -- you can watch your shows even in the absence of WiFi, so long as you have decent mobile connection. Thankfully, that feature comes with new settings that let you choose the quality of the stream, and hence the amount of data you'll use. The update's now live on iTunes if you want to take advantage of the new features... or to give the app another shot.