I don't do video reviews yet so I can't comment on that aspect but for my written reviews with photos, it takes me at LEAST an hour and a half. Typically longer though. I always get envious when I see a reviewer that does excellent reviews (in my opinion), saying they take less than an hour. I'm like, dang!
As for the specific time it takes, it really depends on the product. I said an hour and a half but when I'm doing reviews on underwear, it's more like an hour. Underwear are fairly easy to review and they aren't a complicated product. The more complicated the product is, the longer it will take me.