Not putting effort into the promo doesn't get people excited nor curious for the actual video, if you're not gonna put in the work, then don't even bother with a promo and just work on the full video
You should try to have your shots zoomed in instead of using the default FOV, it helps makes your videos look better and more professional and/or cinematic, depending on what you're going for
You should also try learning the stop motion tools and use them to your advantage, it's better than having flailing and hopping ragdolls with thrusters attached to their hands
The scene at 0:22 was just a still image that overstayed it's welcome, there wasn't anything of interest and the sound effects don't help sell the scene since we're still just looking at the Spy
You shouldn't go overboard on the animations that come with the models, while it can work, it does come off as a lazy excuse to not animate something
You should also try a bit of audio editing, if you can't do much inside the video editor, try editing the audio in a third party program like Audacity to fit better into where they play in your videos, like the Spy saying "forget this!", you could try editing a copy of that audio so that it's more in the left ear and echoed since the Spy is off in the distance to the left from where the shot takes place
And for the three still images of the Engineer exclaiming about the Spy, even for an attempt at stop motion, the lip syncing wasn't very convincing, you should try sounding out the words yourself and try to do the same with the character models over a bigger amount of still shots to smooth out the movements and make it more believable
Also the clip of the Engineer "Spy!" came after the Engineer already finished the mouth movements
And something you should try to improve on in the future is animating more of the body than just one thing at a time, otherwise your characters just look too stiff, like how you'd move your body IRL, especially if you were being more expressive about saying or doing something
Gmod videos are not 100% stop motion.
Many Gmodders would beg to differ, in fact, a lot of people who make Gmod videos, especially those weird/random TF2 ones, have their screenshots folder filled to the brim with screenshots that only have a few adjustments to them here and there to smooth out their animations
But some people do use advanced editing techniques to have transitions between stop motion and not-stop motion, or to have stop motion and non-stop motion happening in the same shot, so i won't criticize you for that
Overall, for your first video, it's a good attempt, but there are things you needs to improve and work on if you actually want to make videos that are funny and exciting
