ipython/ipython — comment on commit dba93d8c6b2b2d2d5597017f73dc25ca6d2e932d
File: docs/examples/notebooks/00_notebook_tour.ipynb line 544
By jenshnielsen:

Just tested the video embed. It looks good however HTML should be imported here and in the next cell.
If the video is encoded as webM and the type changed from x-m4v to webm it also works in firefox that has no support for mpeg4.
I just tested with a demo video from webmproject.org but it seems to work in both firefox and chrome with webM.