Still working on those participles

[david-us.livejournal.com]

I just ran across these two sentences in my text (still working on those participles):

Я увидел его отдыхающим на пляже.

Я увидел Олега, отдыхающего на пляже.

The use of the instrumental in the first sentence is a mystery to me. The second sentence makes perfect sense. With regards to the first sentence, the text has the following note, "... after a direct object pronoun, the participle is placed in the instrumental case and is not separated from the pronoun by a comma in writing." Is this accurate?

I think I'm going to try and steer clear of these participles when able. It's useful to know/recognize them when reading, however. Just for my own edification - would the following sentence be grammatically correct?

Я увидел Олега, которого отдыхал на пляже.

(ref: Modern Russian II, p.875, but I have the 1965 edition.)

Comments

[wolk-off.livejournal.com]

Ditmar Elyashevich certainly had to refine this concept a bit more thorough, then.

[oryx_and_crake]

However to me it makes perfect sense.