The older meaning is obscure, largely redundant, and doesn't really make any sense etymologically, so it's not really surprising that the newer meaning caught on.
(And since we're being pedantic, it's got nothing to do with grammar.)
if the message is getting through, that's what matters in my book :)
That's just useless. And you know, saying "it once was A, now it's B, so it can never be A again" is exactly as "prescriptivist".
Little things add up, and before you know it people are just stringing words together as demonstrated on a million youtube videos.
> The older meaning is obscure, largely redundant
How so? How is the "new one" (which one? heh) not redundant? If you want to say something raises a question, that's an easy way to put it right there. On the other hand, I'm not even convinced that the bastardization of "begs the question" into "raises the question" wasn't simply based on not even understanding what assuming an initial point even could be, of just hearing the phrase without understanding the context and using it as another way to say something or someone raises a question. I certainly don't hear it in common usage, regardless of the phrasing used. You know, if all those other people say they just say it because "most" people do, then none of them actually do have a reason. A billion times zero is zero.
And don't even get me started on people suddenly calling low framerates "lag" :P It just destroys information, and you can call it progress because the hands on the clock moved a little, but I won't.
Except I'm not telling you what you can say, I'm telling you what other people do say, which is descriptivist. You can use meaning A if you want to, but don't expect people to understand you.
>You know, if all those other people say they just say it because "most" people do, then none of them actually do have a reason.
That's like saying no one in the US has a reason to speak English, they're doing it just because everyone else does.
Language is about shared understanding, so most people around you using a particular meaning is pretty much the only reason for someone to use it.
>you can call it progress
I don't call it progress, just change.
Begging (for) the question is a correct literal usage of those words, under both prescriptivist and descriptivist definitions of the words. You're allowed to use the same sequence of words as an idiom in other ways. I can talk about a hot potato without metaphor, and I can talk about begging a question when not describing a fallacy.
It's not the cheapest to encode, but even a baseline H.264 low cpu use profile will beat MPEG-1 or MJPEG anyday anytime on bandwidth and quality.
In realistic cases something like Lagarith was traditionally worthwhile simply because you couldn't read raw video from disk fast enough. I don't know whether that's still true in the age of SSDs.