don't give up so easely
i'm not familiar with the tech of tm2 but i know that tm accepts webm files instead of bik files
you should try those formats
It was kristjan who told me about the possibility but as far as i know he never found a good use for it.
the main problem is the files restrictions.
as far as i know you can use bik files in any dimension but they cannot be bigger then 50 or 60kb depending on the block.
i don't advice using after effects to create the skycolor and stadiumcircuit block because it will first convert your file into a video which rad converts to bik, the file will be huge and the textures will be awefull.. instead use this site
http://www.online-image-editor.com/gifmaker/upload some textures in the same size (256x256 will be ok)
beneath the small thumb there will be a delay 1000 for 10 seconds
add the files and delay needed, and create the gif
you'll notice that it will be a very small file
convert that to a bik file and keep it around 50kb
place it onto any file you want and it will change it texture in the timelaps you chose
this works on skycolor.tga too, also on StadiumFXClouds (place the same file on both) it will make it pitch black in day mood
you can place it on dirtsmoke and dirtmarks too
i did this on my lava mod and when you drive onto it, your tire tracks and smoke will really burn
But i think almost every block can be turned into a bik file
use the main types of blocks and you can make a mod in the size of 2.5Mb
Stadium: circuitD, controlglas, fan (more bout that later) startsign roadcircuitborder, fabric, racesignrubber, warpauvent, roadborder, circuitlogo, platformfloor (look out for this one) roadgrid, the grass and the dirt (is there a way to remove the grass?)
further more i don't advice to work with transparancy on the blocks, ok you can make a type of block dissapear by using a transparent picture between 2 other textures, but when you get close to the blocks you'll notice that it clips (you can see through it)
about the fan... most fun i had with that one. put a transparent explosion in it for example :' ) i also created a running hamster in a wheel, a baby in a washer, electricity... spirals (i made them turn in the opposite direction of the fan which makes them appear straight or turn slower)
need more info? just ask

, i hope this idea brings back some great modbuilders (send them a mail with the idea?) the possibilities are endless
Switching from day to night mood.. from sunny to rainy, from fall to winter, from midievel castles to future textures
the delay between 2 textures can be several minutes in my experiments
good luck.
I had to start modding years ago ..