No, it doesn't modify 如果
or the phrase in between, and there's nothing to do with possessive constructs. I wouldn't even notice it when I speak, but when I think about it, I agree with hrzhu, that it can be loosely translated to is the case
, the actual words don't have explicit meaning here.
I think 的话
provides a short pause, which gives the speaker a chance to actually think about the condition or assumption being said. It sometimes creates a tension, e.g. 如果我杀了你的话...
, you can pause for many seconds here to frighten someone. Notice that 话
ends with the [a] vowel, so people tend to lengthen it when they don't know what to say, and need a sec to think, e.g. 如果他是GAY的话......他就不会喜欢你
.
So the idea is that with 的话
, the 如果
clause sounds more natural, because the condition or assumption being said does sometimes need a sec for you to pause and think. Without 的话
, it sounds quite abrupt, although it does work if you leave it out, in most cases. Personally I call these constructs the lubricant of the language.
的话
means in English. "If, say for example, blah blah blah..."如果...的话
asif ... is the case
. I'm not very sure, but I guess in most cases we can leave的话
out.你想看的话...
. It translates to "If you want to watch..." but literally is, what, "You-want-to-watch type of words"? My best guess for meaning is "(In regards to) the words/case of you wanting to watch..." Does that sound right?