Alex,
Seen it only a couple of times, both in a C130K which had the AAR probe fitted. The first time it started with arcing & sparking around the wipers, then a large plume formed on the end of the probe, at its largest it was about 4 feet across! Quite impressive to see, but as we were about to (inadvertantly) enter a CB, not something I would particularly wish to repeat for the benefit of the cameras.
The second was similar but without the large plume, although we had arcing on the prop tips as well. That time we were flying between CBs - we were on a medevac & had to fly low to keep the cabin altitude low for the benefit of the patient so we had to weave through the weather.
Bottom line is that the phenomenon is very rare & we usually do our best to avoid close proximity with CBs, especially at night where it's harder to avoid them visually & when they look more dangerous because you can see the lightning flashing inside them. You could try the Americans, they have aircraft that chase storms for met research purposes though mostly by day I think so not ideal for filming. Good luck!