Yes, it's on the fly. The only way they'd notice is if they are trying to skip a ways ahead before it has had a chance to convert to wav. They can open an MP3, and start transcribing immediately. Unfortunately, in our case, they normally do verbatims of only a specific part of the meeting, say starting in hour four. They must wait until it has converted at least that much.

Oh, and wav path is \Program Files\NCH Swift Sound\Scribe\Current Files.