Are captured cards considered under opponent's control?

[ultra]

Dark Duncan's Katana again but different angle:

DOWNSIDE: You cannot take control of your opponent's cards.

does this stop the use of

Insightful planning or any capture effect?

Insightful Planning (Capture Special) (RVR021)

Play during your May Do / Must Do Phase.
CAPTURE: Place one Special Card your opponent has in play under this card. During your next Sweep Phase, both cards are swept to their owner's Discard Pile.

im guessing this does stop the DD from using Kane's Quickening while using this Katana.

Just making sure "capture" does not equate to "control".

Thanks.

[prowler7]

Capture does not give control. There are other Effects that can give you control AFTER a Capture effect.