What we see depends on the color characteristics of the light that is hitting the surface to begin with, so the color we see will be different in natural and artificial light. With video, the color we see will change depending on the receptors in the camera and any filters.
Purple, not violet, is difficult to keep the same in different media because purple is not part of the light spectrum. Purple is our brains' interpretation of seeing reflected blue and reflected red. Our eyes have no cone receptors for purple. Because purple is dependent on two other colors, its appearance is difficult to keep constant on different surfaces and in different lighting conditions. Having a smooth uniform and a matte helmet makes this more difficult.
That's all well and good, but this is the 21st century which has brought us TV's so clear we can see sweat actually coming out of pores. But for some reason they're having trouble transmitting the color purple? They didn't seem to have much trouble with the old jersey's, which I never remember looking blue. Sometimes they looked pinkish xD, but I digress, it has been much better in recent weeks. I knew they'd make some adjustments and get it fixed eventually so I never hit the panic button.
Do you not remember the Vikings in the 90s/2000s? On TV, the helmets were purple, but the jerseys looked blue. This was a time before colour filters were really used, so hence the colour difference.
The newer reebok jerseys were the same colour, but filters were already in place that made sure they stayed purple on TV from day 1. The brand new jerseys are different colours, as are the helmets, which is why it's taken a few weeks to get the colours set properly. It's preseason for broadcasters as well as teams, We'll see on Sunday if they got the colour filters working properly yet or not.
I could only post 1 video per post so here's what I remember of the old Viking helmet/jersey's. Just 2 different shades of purple.
This is a picture that I took at the draft party this year.
I would say that the colors in this pic are accurate when compared to how it looked in person.