As a note, just because you see little artifacts on a video does not mean the Tegra 3 can playback hi10p videos perfectly (some vids will show little artifacts while other will show a lot). Software decoding is the only way to go. Unfortunately, the Tegra 3 only gives usable playback on hi10p 720p video when it's OCed to at least 1.5ghz on all cores (tested on my Transformer Prime when I was able to OC up to 1.6ghz). While usable, you still see frame drops during high motion scenes or during panning. 1080p hi10p vids are out of the question.
Even the Snapdragon S4 1.5Ghz dual-core on a lot of new phones also has problems with 720p hi10p videos too - some videos will play okay, some will play fine, others will not play well using software decoding on MX Player. I personally never test hi10p vids using the hardware decoder because no SoC, to my knowledge, can hardware decode 10-bit videos.
I actually have an HTC One S Phone. with one of those S4 1.5ghz dual cores. I just haven't had time to transfer some files to my phone (it has no sd slot so getting files to the phone are harder...) I'll try to run through some tests and give some results. Unfortunately I can no longer edit the frontpage to update the new findings (a new feature of the forum?)
About the Tegra 3. I've seen the Tegra3 in a Nexus 7 in staples play a coalgirls 1080p hi10p episode of anime. It didn't have very much high speed action, and it occassionally dropped a few frames. also the colors were a little blotchy (but really not too bad). It did play though... and was very watchable. This was using mxplayer with the new HW+ setting.