001. IMPORTING THE MP4

1) File > Import > Video Frames to Layers

2) Choose the part you want to import. Click Selected Range Only and Limit To Every 2 Frames. Make it into a Frame Animation.

3) Delete the frames and layers you don't want to use. And then select all the frames and change the frame rate. I'm using 0.8. 

(To change the frame rate: click the time codes and click other and set the delay.)

4) Convert the frame animation to a video timeline. Select all of the layers and convert to smart object.

5) Now we have to resize it. Click Image > Image Size. You can resize it to any size. 

6) The image size still wasn't the size I wanted it to be, so I cropped it.

7) We now have to sharpen the image. Click Filter > Sharpen > Smart Sharpen.

I recommend these settings. But if your image is in 720p, I recommend changing the radius to 0.2 instead of 0.3.

002. FILTERS

8) Now you can use the adjustments to add filters.

These are the settings I used for this GIF
(Settings will change with varying GIFs.)

9) Now we're ready to export. File > Export > Save for Web (Legacy)

10) These are the settings I use.

(You can check the Transparency box if you want to decrease the file size)

Remember, the file limit size on Wattpad is 3M. If your file size is too big, change the image size to something smaller or delete some of the frames of the GIF and click the transparency box.

BEFORE:

AFTER: