Amid the hoopla of Google IO, a few Google-related items sailed by almost unnoticed — such as a cool update to the Android version of YouTube.

For the first time, YouTube will start downloading videos it thinks you might want to watch, whenever you're plugged in and on Wi-fi.

That's great news for commuters, for example, who can now watch videos when outside their mobile coverage zone (or without paying for costly video downloads over 3G).

YouTube, careful to draw a distinction between this and total downloading of its vids (which breaks its terms of service), is careful to point out that you'll still need to be online for the first second when you press play.

But presuming you manage to do that before your train goes into a tunnel, say, you're covered. All you need is that brief second of data coverage to start those marked vids.

Still, YouTube will start choosing and downloading those videos based on your past browsing habits, as well as what channels you're subscribed to. (YouTube had a channel-based design relaunch back in December, which it says has boosted the number of channel subscriptions by 50%.)

Android users will be able to spot the downloaded videos by a small green arrow in the corner. You can also tell YouTube to only download videos you've saved to your "watch it later" list.

As for the non-Android versions of YouTube, such as the much-in-need-of-an-update iOS version? The company says it's working on bringing the same experience across platforms, but won't give any specific timing.

Would you watch more YouTube videos if your phone or tablet downloaded them in advance? Let us know in the comments.