Recorded programmes are being played straight from your V6's hard drive and don't have anything to with the internet connection. So if you're having issues with that, something else is wrong.
If VoD is dropping with your wireless reporting 30%, then you've identified the cause of your issues as insufficient WiFi.
The fact that a reconnection doubles your signal is curious but not surprising - I suspect if your superhub is in default config, that your V6 could be swapping between the 2.4 & 5Ghz wireless bands - preferring the 5Ghz but falling back to 2.4Ghz because of insufficient strength.
If this is the case, and certainly as a diagnostic exercise, the next step could be to separate the bands out into different network names and force every device in your home - V6 included - to connect to one or the other band, manually.
I don't use the SH as a router, but (edited post).... check out post-6 from @jbrennand in this thread for some pointers on tweaking your superhub settings.
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