It’s not exactly becoming for an English teacher to start whining about correct usage of English, and it’s something I try to avoid completely these days. Aside from being fundamentally annoying and probably pointless it also counts as “taking my work home with me”, something I’ve never been keen on.
There are two words, though, which have been so deliberately and perniciously misused of late that something needs to be said. Those words are “theft” and “steal”, as used as in the following sentence;

“When you go online and download songs without permission, you are stealing.”

I’m not going to discuss whether downloading music or films is right or wrong. It’s an issue that gets a lot of coverage these days, and the morality and management of it is a complex matter. Complex matters need reasoned argument, and what we can see here is the complete opposite – the attempt to redefine a word in order to make your case.
the verb “steal” is a fairly simple word, and with only two definitions which apply to its use here. The first is

“to take (the property of another or others) without permission or right, esp. secretly or by force”

Clearly this can’t apply here. If something is taken then it is gone, and the owner no longer has it. Downloaded music is only copied. There is, however a second definition:

“to appropriate (ideas, credit, words, etc.) without right or acknowledgment.”

This would appear to be closer to the mark, however it only applies to cases where somebody is taking an idea and claiming or using it as their own. If you claim a song is yours and sell it, this is the case. If you copy a CD and sell it, then you could also say so, though even now we are stretching the definition quite a bit.
The argument usually made at this point is that the potential sales made from the music or film have been “taken” from the artists / companies involved. But theft does not refer to an imagined future, it applies only to situations where you deprive someone of their posessions or their ideas.

As I said before, this is a complex issue, and the legal definition and policing of it a difficult thing to get right. But anyone who chooses to make their case by attempting to rewrite the language, as the music industry has done here, does not deserve to be listened to. Not only is it deeply patronising, but it has unfortunate connotations of the enforced ‘Newspeak’ of Orwell’s 1984. Anyone who tries such a reprehensible tactic should be treated with deep suspicion.