Is it possible to make your character be controlled by AI, while you watch from third person camera?

For example, I want to create a spell that is a type of berserk. You gain a bonus to various stats, but for the duration of the spell you can't control your character (can't use potions, move freely, etc) and you attack both friend and foe. Is this possible?

Probably not, and getting control over your character once again would be very, very problematic.

Might I suggest setting the player alpha to 0 (invisible) and creating an actor copy of the player to do the "berserking?"

Creating a copy of the player using CreateFullActorCopy also creates a LOT of savegame bloat. I'm not sure about CloneForm though. It is possible to set the camera to thirdperson and following the player, which can then be set to the rampaging creature's position using SetPos.

Yes, I was thinking in this direction as well. The problem is that even these methods are buggy (if used in interiors, for example, it would be hard to detect where to position the player). CreateFullActoryCopy creates savegame bloat, regardless of any steps taken before executing the function, right? And CloneForm is OBSE, right? How come it is better?

You could use CreateFullActorCopy just once after the player exits the starter dungeon to get his appearance, and move this clone to an unused cell like the TestingHall. Then when you need it, move it to the player's location. With some scripting skills, you can make a loop that walks through the player's inventory and pushes any equipped items into an array, then copy those items to the clone and make him equip them, or you can just pretend the berserker state makes you rip all your clothes off and send the clone in naked Make sure to include a check not to copy equipped quest items, as this will bloat the savegame and may cause bugs. Copy the stats and skills by using GetAv and SetAv.

The tricky part is getting the player to move without user input. If you get the clone right, you could walk through the references in the current cell, see if the player clone can detect them, give them a ref if this is true and use something like
"playerClone.startcombat NPCref" to make the clone attack that NPC, then using Setpos and Getpos to continuously move the player to the clone's location so the camera follows. If I recall it correctly, using player.moveto will black out the screen, you might want to avoid that.

Screen black out would make sense if it was temporary though. You character blacks out, and when you can see the screen again you are surrounded by dead NPCs and monsters.