You know how lowering the blacks and raising the whites can give the image some tonal "punch?" Well, it doesn't work well with snow footage. That's because most of the image is at the upper end of the tonal spectrum, which is why lowering the blacks doesn't bring out snow detail, and instead makes it so there's less detail in the trees/people.
Here's an easy trick you can do with the levels to make it look more clear:
(optional: when transcoding GoPro footage in MPEGstreamclip, lower contrast to 80% in the adjustments window before transcoding)
1. Apply 3-way Color Correction
2. Adjust blacks so that they're dark as possible while still retaining detail.
3. Lower mids until entire image looks underexposed.
4. Raise whites to compensate. Make them bright as possible without clipping.
This method will create contrast in the snow and bring out all the details without making dark objects appear too dark.