The ‘S’ here isn’t pronounced. What you are hearing is the beginning of the ‘f’ (or maybe some audio glitches).

The s of très is silent. Pretend like you are saying tre froid. Remember the CaReFuL rule. If a French word ends in C, R, F or L (the letters in CaReFuL), the final letter is pronounced. The s in très is silent since it does not follow the rule. Of course there are exceptions just like other rules that also have exceptions.

Hope this helps!