The bare infinitive is often used in place of the present participle after a noun or pronoun:
I saw him steal the apple.
You heard the student spell the word correctly.
We will watch the students perform their play.
I �m thinking that it is usually used after a sense word (see, hear, watch, etc.), after coming up with these examples.
This form doesn �t have the "while it �s happening" implications that the present participle has. It �s more a simple statement of fact, rather than something that is (or was or will be) going on, as the continuous tenses imply.
Clearer?
Bruce