Only recently started using my N9 for keeping up with the more recent TV series, as such, only recently noticed this "issue".

Scenario 1

1. Internet not connected, but enabled
2. Video plays
3. "Connect to Internet" pops up, video pauses
4. Cancel dialog (or swipe away)
5. Swipe back to video
6. Press Play
7. Video continues

Repeat from the top at intermittent intervals.

Scenario 2

1. Internet not connected, Internet connection DISABLED
2. Video plays
3. "Enable Internet Connection?" pops up, video pauses
4. Select No (Unable to swipe this screen away - unknown why)
5. Swipe back to video
6. Press Play
7. Video continues

Repeat from the top at intermittent intervals.

I have tried watching the videos WITH and WITHOUT any other applications open. Anyone with suggestions or a solution? This is something I could live with if it happened at long intervals (10, 20 minutes) - but I can't seem to find a pattern to what occurs.

One "work-around" that I don't want to use... is actually being connected to the Internet. Most of the time I'm nowhere near a WiFi AP, and would ideally like to avoid the drain of HSDPA.

have you tried
settings-applications-videos-show related videos from the web(or something)

Yeah the connect internet keeps popping up on my n9 for some reason.. Not when playing videos (as i never play videos), but whilst i am doing basic stuff like navigating menus etc. It doesn't happen on my other n9

could it be because the connection you're using is not on automatic? Try setting the networks you use to automatic see if that helps.

I'll try that shortly. Not sure how much difference it would make since completely disabling Internet connection doesn't seem to help either.

EDIT: Added networks I use to automatic (home WiFi). No difference (probably since I'm not at home when I'm watching videos). The idea is to avoid having to be connected when watching videos - currently the only solution for me appears to be to actually be connected (either via 3.5G/WiFi) to a network. The battery life on the N9 despite being an improvement from the N900 in some ways definitely isn't enough to make me want to watch videos while having a 3.5G connection.

I should probably file a bug report on this some time soon.