Whatsapp has just pushed out an updated to their closed beta application, taking it to version 2.12.306.
The update is pretty significant and brings a number of improvements.
Firstly, the app is now able to send video of arbitrary size due to a built-in video compressor. 300 MB files are sent easily.
Secondly the app is now able to receive documents from others, and documents can be sent via the OS share function (though not directly attached from the app).
Lastly the app is now missing the page where one would purchase a yearly subscription, after Whatsapp dropped this fee.
The WhatsApp beta program is closed, so not available to the general public, though it does not usually take too many weeks for features to come to the main version of the app. For now you can download the public version of the app from the Windows Store.