Android (4.0.3+, rooted): Recording screencasts on Android can get tricky. Some apps only support certain devices, and all of them require root access. SCR Screen Recorder is one of the first that supports a broad array of devices, including Tegra-powered Android tablets like the Nexus 7.
Once installed, fire up the app and tap the record button to start your capture. You can tweak the capture settings, like frames per second and screen resolution. Once your recording is complete, it's stored to your SD card.
The app comes in two flavours, a free and a $6 "pro" version. The free version keeps your recordings to three minutes and applies an SCR watermark on your videos, while the pro version removes both of those limitations.
The developers of the app point out that it's in beta, and it may not work on all ROMs and devices, but it worked like a charm when we tried it out, as long as you're using a device with 4.0.3 or higher (although 4.3 doesn't seem to be fully supported yet). Hit the link below to give it a shot.