playing vr videos not working

hi, ive had my headset a while now but haven't used it for a good few months. i just put a few videos, on a website they play in VR but i downloaded them and they are in sbs. when i view them in gallery they just play sbs, how do i play then in vr like they should be played. thanks

also what ads do you recommend for playing videos either 3d or vr. thanks again