The Video Messaging feature of Skype which was in beta testing and was limited to 20 free messages before a Skype Premium subscription for $4.99 a month was required for continuous use, is now completely free to use. You can send and receive video messages without subscription.
The Video Messaging feature is available for Windows, Mac, iOS, Android, and BlackBerry. Surprisingly, there's no support in the Windows Phone client for Video Message sending. 