Is it safe to transfer videos using WhatsApp?
What steps are taken during video transfer to ensure privacy?
Your best bet is to read this:
Here's a small section copied and pasted:
Our Commitment To Data Security
WhatsApp uses commercially reasonable physical, managerial, and technical safeguards to preserve the integrity and security of your personal information. We cannot, however, ensure or warrant the security of any information you transmit to WhatsApp and you do so at your own risk. Using unsecured wifi or other unprotected networks to submit messages through the WhatsApp Service is never recommended. Once we receive your transmission of information, WhatsApp makes commercially reasonable efforts to ensure the security of our systems. However, please note that this is not a guarantee that such information may not be accessed, disclosed, altered, or destroyed by breach of any of our physical, technical, or managerial safeguards. If WhatsApp learns of a security systems breach, then we may attempt to notify you electronically so that you can take appropriate protective steps. WhatsApp may post a notice on the WhatsApp Site or through the WhatsApp Service if a security breach occurs.