My computer running OS X 10.9.4 has permission to allow downloads and updates in the background. Since this latest OS update, it downloaded iMovie 10.0.4 about 850 times (one download per minute @ ~2 MB/sec) and installed it once (that I know of). It's done this previously, took me a while to realise that it was happening again.
All the best.
Edited by IQatEdo - 7/4/14 at 9:01pm