Hi suede -
As Uncle Bill said, each word has a different meaning. His post is a little more technical - I'm going for the "usage-sentence" form of explanation!
"Behold" is more Biblical, but it's also used in formal or mock-formal situations. You might say something like, "Princess Diana's beauty was wondrous to behold." That just means it was a treat to see how beautiful she was. This word is also often used in the expression, "Lo and behold," which is a bit archaic but still common coin (if a phrase can be both those things at once!). You might say, "I rubbed this old lamp I found in the attic, and lo and behold! a genie appeared!" It's an expression of something happening either suddenly or unexpectedly.
Behold can also be used ironically, because it is "old language." For example: "Behold, a cell-phone-user running a red light." The use of the word here makes the statement ironic, as if it's an uncommon thing to see a cell-phone-user running a red light, when really it's not.
Seeing can be purely visual. You see a blue sky, autumn leaves, a dog with a waggy tail. You see someone commit a crime, make a pass, run a race etc. On the other hand, you don't see television, you watch it....You could see a television in the store and decide you liked that brand, and buy one - to take it home and watch it. You don't see a baseball game - you watch it. But you could see a certain player: "I saw Yogi Berra in the last game of his career." You can also see a play: "I saw Cat on a Hot Tin Roof last night - it was really good." If you saw it on tv, though, rather than live, you might be more likely to say, "I watched..." as in, "I watched a rerun of 'Friends' last night." Or: "I saw the rerun of 'Friends' when Joey pretends he has a lot of dance experience to try to get a role in a musical."
Watched is more general,
saw is more specific (you indicate the instance/particular item you saw).
Observe is, as Bill said, for more than just seeing. A doctor might observe a patient's reaction to a certain drug; said doctor would not just be seeing what happened, but extrapolating from it. "See" is more of a passive activity (there's an oxymoron, if you like!); "observe" requires a bit more engagement on the part of the observer. You observe effects of actions; you observe results in a scientific study in order to draw conclusions, possibly for publication.
You might observe a traffic accident, even - though you're more likely to witness it.
So, for a social phenomenon, you might say:
"I see this social phenomenon occurring," or
"I observe this social phenomenon occurs" (and you might add, "when" and then give a time or instance)....
"I see this social phenomenon of the group dynamic in crowded situations, when people follow each other like sheep."
"I observe that, in crowded situations, people fall into a group dynamic and follow each other like sheep."
Urg. This may not be the best explanation you get! I'll see how others weigh in on this one....That's my best shot, it being late an' all....!
