I have a H.264 (ex-MOV, ex-Flash) video of 550px x 250 px. In the HTML player (videojs), I can easily set its size to 640px x 290px and it still looks OK (only a 16.363636% increase in display size).
Or should I increase it's size in "real pixels" by exporting it as H.264 from, say, Avanti or Handbrake at a bigger size? In Avanti, under "Frame size" I specified 640 x 290 and the file size increased by 8% and data rate from 200 kbps to 215.
What are the trade-offs - would enlarging via HTML be stressful for low-end CPUs? Is the 8% increase in file size and kbps worth it for the extra quality, if any?