Question regarding in-site 'Search' feature...

I was just wondering why certain torrents don't show up when I use the 'Search' button on ET itself, but when I use google or other search engines to search for them, I get results from ET that I can't find on it's own search?

To clarify: I found a torrent for the 1974 William Shatner movie Impulse through google, but if I search 'Impulse' on ET, or even 'Impulse 1974' or 'Impulse (1974), et al, I get nothing. Well, I get a lot of results, but I don't get that movie or that page itself.
Just a few minutes ago, I searched 'Penn and Teller', looking for the new episode. I didn't find it, so I tried 'Penn & Teller S08E09'; 'Penn and Teller S08'; 'Penn & Teller S08', and so forth, and also didn't find it. Directly after that fruitless search, I went to google and tried 'Penn and Teller S08E09' and the first result was from ExtraTorrent. Que?
It's happened a few times with other stuff, as well.

It's not really a big deal, or even an inconvenience, but it's certainly odd... at least to me.