It's way better opium, much more seductive. Entertainment has the same relationship to real life that porn has to real love: it looks like something of value, but it has none of the real content. Entertainment is fake living, just like porn is fake love. Thanks to mass media and the Internet, entertainment has replaced religion as the opium of the people.
If I'm interested in making progress, I have no time for entertainment. TV, radio, fiction, movies, browsing the web, live shows and concerts: any venue where I'm just a consumer, not a student or creator. Entertainment effectively kept me from making progress with love. Entertainment has no value, it just occupies time. It keeps me occupied while I do no work. But if my life is a void, it fills the void. A lot of lives are voids, so entertainment, like porn, has its place. A sad place.
Mindfulness would prevent that. The spiritual path is extraordinarily demanding. Love demands I give all I have to give. There's an old saying that if I take one step toward god, god takes a hundred toward me; god does all the heavy lifting on the spiritual quest. If I do everything humanly possible to make progress, my wisdom will do all the rest, the 99%. I have to examine how I spend my time, looking for ways to make all my activities count toward making progress. Doing anything mindfully makes it count. But some things can't be done mindfully. I can't harm myself mindfully.
The same goes for activities with no value, things I do just to kill time, e.g. entertainment. As Thoreau famously said, "As if you could kill time without injuring eternity." Any venue where I'm just a consumer is worthless. It fills up my time and keeps me from making progress with love.