I'm a native speaker and I got this wrong. Wouldn't "I would do something else" rather be "Jeg ville ha gjort noe annet"? The way I see it, this sentence translates to "I wanted to do something else" in English.
"Jeg ville ha gjort noe annet" would have been "I would have done something else".
Det du snakker om er 2. kondisjonalis, mens denne setningen er 1. kondisjonalis :-)
To perhaps clarify the above further, can a sentence such as this one either be conditional or simple past ("I wanted to do something else") and the context has to indicate which of the two it is meant to be?
Until now I had thought of "ville" etc. as mainly the simple past forms of the modal verbs, and so by default I would understand the given sentence as a non conditional simple past sentence. Is this wrong?