The batteries are not reliably meeting the contacts at both ends. Either there is some oxidation on the batteries or contacts which jiggling removes, or the batteries are loose in the compartment.

Bad connections at the battery contacts. They often corrode due to chemical leakage and Galvanic effects. A quick jiggle dislodges the insulative corrosion products ( if it's not too bad ) and gets things going again.

I have noticed that rubbing low life batteries vigourously seems to restore some power to them.

whether this is purely from the heat generated or perhaps some sort of electrical transferrence from my body I dont really know, can anyone enlighten me.

While I don't understand exactly what happens on a chemical level, I am certain that it is the transfer of heat (energy) from your fingers whilst jiggling the batteries that by some mechanism means enough energy is provided by the batteries to complete the remote function. Taking out useless batteries and warming them in one's hand will often eek a little more life out of them. An extreme example of this is my camera battery - after a full charge, when snowboarding in -10 to 0 deg celsius temperatures, the battery will last only a few minutes whilst recording video. I learnt that keeping the camera next to my body, I could increase the useful life somewhat. A 'dead' battery on the mountain suddenly becomes almost full when returned to the warmth of the chalet.

Oxides form on the battery terminals and the device contacts increasing their resistance.  Car battery terminals are smothered with grease to prevent oxidation.  I suspect that many batteries are thrown away before they have fully discharged.  I just turn the batteries in remote controls and they last for years.