Construct2, the popular visual HTML5 game engine, just released version R218 beta. 
From the release notes:
New this release: support for NW.js 0.13.0-alpha6 with a few bug fixes, experimental support for recording a video of the canvas with Firefox, and pressure and size information for touches, particularly relevant for the iPhone 6S with its 3D touch support.
NW.js 0.13.0-alpha6
Hot on the heels of the alpha5 update, alpha6 is now out with more feature support and some important bug fixes including allowing NW.js features to work in preview mode. This C2 release also fixes a bug that was causing a blank screen after export. Be sure to head to scirra.com/nwjs to download the latest alpha6 release of NW.js, which is out now.
Canvas video recording
Firefox 43 adds a new feature that enables recording a video of canvas elements. Note Firefox 43 is due for stable release in December, but you can try it now using Firefox Beta, Dev or Nightly. The User Media object has been extended to allow recording the canvas, and Construct 2 has a new “canvas recording” example that demonstrates how to use it. Previously recording a video of your game would involve using separate video recording software, so it could be handy to instead record it directly from the browser.
This is a pre-release feature, so there may be some bugs or quirks. I noticed for example Firefox only appears to encode video at 30 FPS with the VP8 codec in a WebM container. If you need video in another format, you may need to transcode it afterwards. It also does not currently include sound, although it may be possible to add that later on.
Changelog
Add User Media: experimental support for recording a video of the canvas [currently Firefox 43+ only].
Add Touch: experimental WidthForID, HeightForID and PressureForID expressions, to get a given touch’s area and pressure. This should also report the pressure of touches on the iPhone 6S (although we do not have a device to test this on yet).
Bug Fix NW.js plugin: caused blank screen in NW.js 0.13
Bug Fix IAP: could have failed to restore purchases on Android
Bug Fix Using savegames could crash if the browser had blocked access to storage
Bug Fix Preview & debugger could crash in Firefox if cookies had been disabled in Privacy settings