iVideoMail is a plugin that offers video recording and posting options in Mail.app.

It installs itself as a Preference pane in Mail.app.

The pane allows you to select the size (320×240, 240×180, 160×120), codec (MPEG 4, Apple’s H264, Sorensen 3) and compression ratio for your video recordings:

You can install its icon into your Composing window using the Customize Toolbar option.

Clicking on that icon, opens a video recording dialog with options for specifying the video source:

The resulting video clip is embedded in the message and ready to send.

iVideoMail is shareware (USD 10) and available from the developer’s web site.