According to recent reports, it seems that YouTube for Android has recently added an option to watch videos in 1440p resolution, as long as the uploader has made their videos available in that resolution, of course. What this means is that LG G3 owners will be able to watch videos that takes full advantage of their QHD displays.
However we should point out that this option is only available for handsets that have a QHD display. This was tested using non-QHD devices like the Nexus 5 and the HTC One M8 but the max resolution offered was 1080p Full HD. It is unclear if this feature has been extended to other QHD devices like the Oppo Find 7 and the Vivo Xplay 3S, but if you own either device, let us know in the comments below!