When you select a noise transport or video layer inside Smode, you can either seek into it with the mouse on the
Thing that can be played out of a Timeline or Function Cue and that doesn't need to be inside an Animation Bank
row, or click on "Create Local Player" to play it as a loop.
Note that video streaming is disabled on Smode Synth.
Once the local player is created, you can select it to get animation parameter (such as playing it back and forth inside the "playing mode" row). Note that a local player can be drag and drop into any other video layer.
If you want to put your video inside a Timeline of course you can then check out the Timeline section of the doc.
By default the local video player will loop, but you can play it once also if you want.