GIFs replace video in Email Marketing

Recently, we are seeing many cases of heavyweight GIFs being used in email marketing (Click here to see an example from Desigual). These are mainly video-based marketing campaigns that are adapted to the email channel with this resource. GIFs seem to us to be an effective way to replace video in email, but Could we be losing users due to the loading time of GIFs that weigh several Mb?
In general, the speed of today's connections allows images to be downloaded almost immediately, but if we think that mobile devices are becoming more and more important and mobile connection can cause more problems (as well as consuming our data tariffs), the GIF may not be the optimal solution.
There are interesting tools such as Viwomail that allow us to use video in our emails in a pretty consistent way: it shows the video in the email clients that support it, and in those that don't, it replaces it with a GIF with a mute icon that when clicked leads to a web version with autoplay. It's an option to consider, but many of us are still wary about the weight and loading time of these GIFs. Therefore, we consider other ways of integrating video into email, not as eye-catching but effective:
Play icon: 
The user knows what it means and knows that when he clicks on it he will be able to see the video playing, although it is true that it does not attract as much attention as the moving GIF that already shows us the content of the video automatically. Here we can see how TOUS uses it in one of its latest campaigns:

Player Frame:
If in addition to adding the icon, we introduce the frame of a player, the usability increases and invites the user to click more powerfully.

Finally, to take advantage of the potential of the GIF without risking too much file weight, we can opt for a short animation The progression does not need to faithfully mimic the video:

There are ways to implement video so that it plays in those email clients that support it and displays a fallback image in those that do not. We will go into this technique in more detail in future articles.
What do you think is the best way to include video in email marketing? Have you had problems with the loading time of the GIFs that replace them? Have you tested different ways of doing it?