I'd be a touch wary of taking-in everything you might see on You Tube and potentially introducing methods that are unnecessary and counter-productive

I'm not doubting the findings, but I don't think that it offers anything in the way of delivering a better result and it is not necessary to restrict the inlet flow at all. It would be misleading to imply it was somehow necessary when infusing parts

Looseness in the bag around the inlet when resin begins to flow is not an issue to worry about, as mentioned earlier and assuming that the bag is perfectly sealed, everything will tighten once the part is closed-off and pressure equalises. 

I've infused hundreds of parts to date, many of them quite small and relatively quick to wet-out and have always had a consistently perfect cosmetic finish. The use of resin breaks sized in proportion to the part size/infusion speed and allowing a small amount of resin flow after closing-off the vacuum port has been more than enough to ensure those consistent results. 

I've not yet encountered a single scenario where choking the resin flow would have been desirable. 

On smaller parts, in particular, choking the resin flow tends to lead to the gas in the resin becoming greatly expanded as the vacuum pressure at the front has a bigger impact. Whilst this might reduce when both ports are closed-off as pressure equalises over the whole part, it feels an undesirable method of trying to achieve a void free finish, especially where resin is likely to reach the exit fairly quickly.

The appearance of the gas is likely to be far more prominent and not just at the front. At the extreme, it's only been the sudden appearance of lots of large bubbles across an part being infused that's alerted me to the fact that the bottom of the inlet tube has vacuum sealed itself to the base of the resin pot. 

As an aide and it's been debated a few times before, I don't bother with degassing any more either, prior to infusion, as I've found that it doesn't deliver a completely gas-free resin or impact on the part's cured cosmetic finish. Some swear by it, but I've yet to find any cosmetic difference in results, even on more complex-shaped parts.

The OP's issue was voids and/or dry areas around the inlet, which seems to indicate a slight starvation of resin in this area, so it appears that his previous process might have been restricting the flow of resin towards the end of the infusion. I don't think that introducing a restriction of resin flow would help matters at all and would be more likely to introduce unwanted cosmetic issues