First of all IT has limitations. It's best seen when Goku comes back to Earth in Trunks saga. He uses a space ship and at that point he has learned the IT. So why did he came back with space ship then ? It's because the IT has a limitation and that's a long distance. Which was also stated in that video. Also he only used IT in fights in both anime and manga. In movies he uses IT for planetary trips
Also about cannonity of that video I think it was also mentioned in the manga (i'm not sure if someone has a scans please post). And from Saiyan saga to Buu saga it was stated only 2 times that the planet will be destroyed ( Vegeta with Galick Gun, and Cell with Kamehame), it was stated by King Cold that he and Frieza can both destroy Earth and the planet destruction was shown 4 times:
1. Vegeta destroying Arlia (anime filler)
2. Frieza destroying Namek
3. Frieza destroying Vegeta (as special)
4. Kid Buu's planet busting rampage
So even if you add movies you can't come up with 30+ planet bustings and statements combined.
And also with an increase of KI person doesn't came up with exponential power increase. It was explained in Daizenshuu. Cause we all now that when transforming into Super saiyan Goku had ki 50 times greater, and it was stated in Daizeshuu that Super Saiyan makes you 50 times more powerfull, so it increases the power lineral. And I personaly think that both Moon busting events are illogilities (which DBZ has very mutch), since more powerfull characters later didn't have such ability, and basicly it was ignored after Sayain saga. Cause it was shown that Frieza had more powerfull fighter than both Nappa and vegeta were in Saiyan saga. "
P.S. Don't get me wrong about the DBZ. I'm not some DBZ hater. Personally DBZ is my favorite cartoon show ever. And I already expressed my opinion about Nappa vs Tony.
Instant transmission only has one limitation, goku has to know where he is going. That is the only limitation. Goku used the spaceship in order to set him on course to earth, in fact looking at things like that is very silly as most people use spaceships even if they could travel solarsystems in seconds. Goku used IT to get to new Namek which is not even in the same solar system as earth. Kid Buu used the same technique to travel dimensions and get to other galaxies, (he did not have the limitation that goku had). The step up from anime to movies is that goku went from travelling to different solar systems (to get dende), to travelling to different galaxies (to find Broly). IT has no speed limitation, it is instant (at least that is what it seems to those without IT).
As for planet and moon destruction, you have to remember that Kami is a "god" in DBZ universe, therefore those with power on his level should have "god-like" feats, such as master roshi destroying the moon, or piccollo destroying the moon. Destroying the moon was the pinnacle of power feats in dragonball, however, dbz was far more powerful. Before moon busting, there was island busting and mountain busting, I don't think that it is illogical that as they become alot more powerful they can destroy the moon. King Vegeta with a powerlevel of 10000 destroyed 3 planets with 1 attack, hence why Vegeta and Nappa should be able to blow up Arlia (anime filler is not necerssarily inaccurate). Mortein has explained how frequently the power to destroy a planet has been stated. In fact in DBZ characters have the power to destroy planets, solar systems, galaxies and even the univerese. It is hard to imagine that powerlevels are linear when this is the case.
Now I will examine the possibility that powers and powerlevels are linear, or that it is not:
Linear: ssj transformation enhanced all attributes 50 fold.
In addition Kaioken did the same thing; e.g. kaioken * 10, multiplied all attributes 10 fold
In fact all transformations such as great ape, enhanced powers in a linear manner
however, when the z-fighters trained to increase their base form, there powers appear to grow in an exponential manner, you may ask for proof, and so I will name but a few instances.
Piccollo went from mountain busting to moonbusting: A mountain has a mass of 3.041409x10^15kg , whereas the moon has a mass of 7.347 7 × 10^22 kg , that is 7 orders greater.
goku went from running 100m in 8 seconds (27.961703651 mph) to being faster than lightning (270000 mph) in dragoball.
Goku did not become 10000 times more powerful in powerlevel term ( increase of 4 orders), hence you can see how some people reach both conclusions.
I will not accuse you of being a DBZ hater, as I can tell that you are not, you have a good knowledge of DBZ and are right to have an opinion, however, I am just trying to enlighten you on why your opinion may not be valid as such, due to the fact that there are some inaccurate statements in your argument..
Final point: to provide more evidence to my theory that increasing base powerlevel is more valuable than transformations is comparing ssj2 adult gohan to mystic gohan. Gohan went from slugging it out with dabura to mopping the floor with super buu, whereas gohan's transformation into ssj2 did not have as much of a power increase (Even Pikkon mopped the floor with cell).
Hopefully this won't go on forever and ever (lol) but awaiting your reply.