I created a gif to use as a login screen... so I used a hud object to display the image.
The issue is the gif uses a ridiculous amount of memory. So I was wondering if there was any alternatives.
Embed it in a browser, but even then, it's not a good alternative. Odds are, the gif's been so color compressed it's gonna look really bad by comparison to a static title screen.
I wouldn't recommend embedding large GIFs in a browser control. Most large GIFs that I see load painfully slow in any browser. In some cases a GIF even loads in pieces, so it looks like it's "buffering".

In this particular case, I would actually expect Dream Seeker's map to be more responsive than the browser control, and display the animation right away, rather than gradually.

However, Dream Seeker does not correctly interpret a GIF's delays, so you may need to convert it into a DMI, so that you can fine-tune the playback speed. This can be done by creating a new icon file, clicking Graphic -> Import... (or simply pressing CTRL+I), and choosing the GIF to import.

Unfortunately, I don't think this will have any real effect on memory usage. One way of reducing it might be to have one large icon to represent the still areas and a bunch of animated icons to represent the animated areas. This could be very effective if there are identical areas. Of course, this will only work if the icon actually has still or duplicated areas.

If that method doesn't work, you might want to consider slightly reducing the total number of colors in the animation. This can be done by running it through a posterize filter in any capable image editor. You might need to repeat this for each frame. You could also try saving with indexed colors. Depending on the complexity of the animation, you might see a huge reduction in memory usage, with minimal loss of quality.
I think honestly, the ideal solution is to not do it at all and do something else.

If you are trying to play a video in Dreamseeker, and you are set on using a gif, don't.

Either use an engine that supports video playback, or don't do the video and create your own animated title screen using objects on the screen. Anything you make yourself competently is gonna look god-tier next to a poorly compressed video being played back frame-by-frame with PNG compression or GIF compression.
I'm not sure if it's fair to call this a video. That depends on how many frames it has. If this should be considered a video, you could actually embed an FLV or MP4 in the browser, rather than a GIF. Obviously, this requires Flash or HTML5. You would also need a way to make it loop and to remove all video control interfaces.

You should also take a look at DeeUnderscore's dmi_browser. It demonstrates DMI playback in the browser. With some modification, this might be better than using GIFs.