Samsung Galaxy S6 — Whatsapp videos are not playing

Hello,

Can someone help me? I have searched the Net and haven't found a solution to my whatsapp woes.

I have recently purchased a new Samsung Galaxy S6. WhatsApp came pre-intsalled on it.

I can receive videos on Whatsapp, and they download easily too. However, the problem arises when I try to play the video. When I press on the downloaded video, nothing happens.
To make it play, I have to go back to the main chats page, then enter the specific chat (of the video sender) again, and press the video. And voila, it plays!

Whatsapp FAQ says I need to update Google Photos from Play Store. Did that. Nothing changed.

A couple of websites said I need to un-install Google+. However, Samsung S6 only allows you to Disable Google + (which I have done) but doesn't offer the option to un-install. That hasn't helped either.

Then some websites suggested I should un-install WhatsApp and try re-intsalling it. Again, Samsung S6 doesn't allow me to un-install the app. I can only disable it. And then Update it from Play Store. Done that too. Hasn't helped.

Does any know what this problem is and how it can be solved? Please help! I'm very worried.