It isn't nearly as effective. I've done both - I was an exchange student to Germany, (Landed with 1 year of US highschool German, maybe 150 words.), and was thinking in German in about 10 months. (I was also 17/18 years old, which makes a huge difference.) For the last few months, I've been trying to get more functional than my "taqueria Spanish", and have shifted to listening/watching mostly Spanish-language media.

It helps, but is nowhere nearly as effective as not being able to escape it. In Germany, I remember going to bed exhausted with a headache quite a bit for a period of months, roughly the phase from when I was barely functional to when I was able to take part in class in non-stupid ways.

Watching TV for a couple hours is nothing like that.