Get this now: WhatsApp Video Optimizer for Windows Phone
WhatsApp is one of the most popular messaging clients around, especially for Windows Phone users. One limitation though with the app is the inability to send particular videos due to their size. Whatsapp force-edits (shortens) your video to meet the 16 MB requirement for sending videos, which is a bit odd.
Luckily, there is now a solution through a free third-party app called WhatsApp Video Optimizer.
AIVAnet 