To my great surprise, 24-30 fps full resolution HEVC (h265, libx265) encoded videos can be played back under Maemo-Leste, on Droid 4 with cpu alone!

By keeping bitrate low and using the -tune fastdecode option, mplayer (and sometimes mpv) has no trouble keeping up with the video! Very small filesize, acceptable small screen quality. Much joy!

Here's a sample ffmpeg line i just encoded with:
ffmpeg -y -i $1\
-filter:v "hqdn3d=0.0:0.0:7.0:7.0,smartblur=1.9:-.24:0.09:1:0.0:0.0,scale=960x540,setsar=1:1,eq=con trast=1.20:brightness=0.08:gamma=1.15"\
-filter:a "volume=1.4"\
-movflags faststart -c:v libx265 -crf 30 -pix_fmt yuv420p -preset medium -tune fastdecode -auto-alt-ref 0 -metadata:s handler_name=ClortVids\
-c:a libopus -b:a 56000 -frame_duration:a 60\
out.mkv
So this 2 hour film came in at about 280MB. 32 seconds is just 560kB.

http://0x0.st/-pE1.mkv

h265 does great for lectures, with static backgrounds.
http://0x0.st/-pEf.mkv

Playback cpu% (one core) on the omap4 is ranging from 75-98%, so higher bitrates and/or framerate films could be problematic.

Still, it's very nice for me. Small files, films and lectures watching on-the-go!