The issue isn’t that these things kill sales completely, but that for a significant sector of the market, a purchase was never even thought of, because these videos are available and “good enough.” You talk about the sales numbers for Life is Strange, but Jacksepticeye’s (commentated, so slightly different, but still relevant) playthrough videos for the first season each have over 4M views, and somehow I don’t think a significant number of those were from people who purchased the game and decided “eh, I’ll watch someone else play this for eleven hours instead of/in addition to my own full playthrough.” That’s on top of sales and bundles, of course, and Life is Strange was involved in a lot of them.
Telltale was even worse off where sales and bundles were concerned, as already mentioned earlier in this thread. I think the only Telltale game I paid full price for was Poker Night on release, and that was a $5 game that also got me a TF2 hat when that was relevant. The only one of their adventure games I specifically bought by itself was The Wolf Among Us…which I paid a bit over $10 for on Xbox LIVE, when only the first episode was out.