Can I get some help?

I also notice that your camera footage is at a higher resolution than your edited footage. The picture size difference between the videos is a giveaway. Try exporting your footage at the same resolution that you shot it at.

If you tell us what camera you are using we can probably give you some help to get better results.

Your camera shoots 4k video. It is unclear from the limited information on the Panasonic website, whether is has an option to shoot HD. So, at 4k resolution you will get some flicker when panning, just like a movie, because of the shutter speed. Usually, 4k cameras shoot at 30 or 25 frames per second, so there will be no way of changing that. It's just the nature of the beast. I had a look at the Microsoft page for Movie Maker. Even less information there!. It does not mention 4k, so I think it may not be suitable for your needs. I looked at the choice of output resolution in Movie maker which showed a maximum of 1920 x 1080, which is HD, not 4k, so I don't think it is capable of outputting 4k whose resolution is 3840 x 2160.
If you must use Movie Maker, make sure that you set the output to the highest possible resolution. Looking at your edited clip, I would say you exported it at a resolution of 854 x 480, which would account for the smaller size picture and the loss of quality. Did you do any picture enhancement in the edit, as the lighter areas are now over exposed in the exported version.
I would suggest that you thoroughly read the FZ1000 manual and the instructions for Movie Maker. Also remember that Google is your friend. Hope this has been of some help.

As an added thought. If the FZ1000 does shoot in HD, and has the options in the menu to shoot at 1080 50p, use that setting, and set the bit rate to the highest possible (ie 24Mbps or higher). It may use more of your memory card, but the results will be so much better.

In the 2 clips you posted in your first post the exposure of the original footage looks fine so check that your computer monitor is set up to display a good image. Yes, software like Movie Maker can be very limited in what they can do. Fine control of exposure and colour balance, etc, is what you find in professional editing software. There are quite a few consumer video editors available, both paid for and free, so it may be worth your while checking out some of the others.

1920 x 1080 is the picture resolution for full HD. The number 60i next to it refers to the number of frames the camera shoots per second. In this case 60. The "i" after the 60 means "interlaced" where 30 frames or fields are added to the other 30 to give a final frame rate of 30 frames per second. You will get less flicker when panning if you use the setting above this. In this case the "p" after the 60 means "progressive" where instead of interlacing the frames they are presented one after the other giving you a frame rate of 60 frames per second (computer monitors display their pictures progressively). The bit rate of 28Mbps is the highest in available in the AVCHD format. The higher the bit rate, the more detail recorded in the image.
If you shoot using MP4, you will see that your camera can shoot in 4k resolution at 30 frames per second. You will see that the picture resolution is now 3840 x 2160 giving much more detail in the video. To edit 4k you need an edit programme that will open 4k material, and a decent computer to run it. The other possible downside to 4k is the amount of data it produces, so make sure if you use it you have some decent memory cards available for your camera.
I would seriously suggest you search You Tube and Google for some tutorials to give you an understanding of the various standards and technical terms. I say this because of your comment about not understanding much of my previous post. It will help you and make shooting videos much more pleasurable.