This is what it does:

Add support the Remote Power On function in Android 8 for PlayMemories Mobile software
Improves the overall stability of the camera

Note: If you have the RM-LVR3 Live View Remote accessory, it will also be necessary to install the RM-LVR3 update as well.

Mark,

Please check out this post that discusses the bugs this new firmware has, post #26, by Steve Digges who uses five of these cameras. I use three and will hold off on the update.

http://www.dvinfo.net/forum/sony-4k-ultra-hd-handhelds/535946-sony-fdr-x3000-any-input-2.html#post1944671