As another German, I can confirm that the “first e in mesmer” way is how Germans would pronounce it. See for example 11seconds into this German video also officially from SUSE’s YouTube channel - a SUSE employee and German native speaker who is moderating a series of talks is using that pronunciation.
It’s just a tiny mistake that most Germans are used to hearing Americans make all the time (see also Porsche which is also not pronounced porsh, nor por-shay, but porsh-eh) and will politely ignore, but since this aims to be an educational video, should be pointed out to be slightly incorrect
The pre mixed spices list their contents and it’s not that hard to come up with something similar by just using the individual ingredients.