Video shared from this source has the following caption.
هؤلاء مسلمو بورما يعذبون فقط لأنهم مسلمون ... من منكم يشعر بوجعهم ما عليه إلاّ محاولة نشر الفيديو على صفحات عالمية ربما تساعدهم ... و أدعوا لهم برطاجي جيم لصفحة Video Live
These Muslims of Burma tortured just because they are Muslims... those of you who feel their face has only attempt to publish the video on global pages maybe you help them... and pray for them to share Jim Page Video Live
I don't find the source to be reputable. With 3.1 M views and 13k shares, is this description legit? They're singing. It sounds like an anthem. Some of the comments indicate they're soldiers. That seems far more likely.
They're held in a cage submerged in the water with their head safely above the water line.