Services like Apple TV or Amazon sometimes offer 3D versions for purchase.
Even if you successfully download a 3D movie from Filmyzilla, you still need the correct hardware and software to actually watch it in 3D. filmyzilla 3d movies work
If you don't have glasses or a TV, sit 12 inches from your monitor. Cross your eyes until the two images on screen become three. The middle image will be in 3D. If you cannot fuse them, the file is broken (common with Filmyzilla uploads where the left and right frames are from different timecodes). Services like Apple TV or Amazon sometimes offer