Adobe PDF with embedded Gifs?

Explanations:

In Joel's document there are 15 named icons:

icon[0]=Muybridge_01
icon[1]=Muybridge_02
icon[2]=Muybridge_03
icon[3]=Muybridge_04
icon[4]=Muybridge_05
icon[5]=Muybridge_06
icon[6]=Muybridge_07
icon[7]=Muybridge_08
icon[8]=Muybridge_09
icon[9]=Muybridge_10
icon[10]=Muybridge_11
icon[11]=Muybridge_12
icon[12]=Muybridge_13
icon[13]=Muybridge_14
icon[14]=Muybridge_15

See importIcon here: https://opensource.adobe.com/dc-acrobat-sdk-docs/library/jsapiref/doc.html#importicon

In Joel's script you will find "interval.count" which is the number of frames/icons to loop.

And "interval.maxLoops" which is the number of repeats.

You can change the name of the field and the name of named icons in these lines:

var icon = this.getIcon("Muybridge_"+pad(interval.count,2));
this.getField("Muybridge").buttonSetIcon(icon);

Take a look at this example file. If it does what you want, I'll share the technique.

https://www.dropbox.com/s/mgo4u7s2xlqgzlz/PDF_GIF.pdf?dl=1