My script works as an action but not as a script

Then what you used to convert the action to a script has a problem. What did you use?

It has a video timeline and your go to end seen to have set 4 29 and 30. You may not have rendered  out a video file but you have a video in the making.  You seem to have extended the layer to play for some time at a 30fps rate.  I would have thought a 4second 30FPS video would have 120 frame though. So 29 does not seem right to me

Will these values be valid for all your video timelines. You stated you clicked on a got to end button will all your video timeline be 4 seconds and have 29 frames and a 30fps rate? you scripy woul most likel need toe finf the enfs s set the correct values you neen  Seconds frames and  rate vakued to the function you created from the action manager code.

#target photoshop

cTID = function(s) { return app.charIDToTypeID(s); };

sTID = function(s) { return app.stringIDToTypeID(s); };

function setVideo(seconds, frame, frameRate) {

var descriptor = new ActionDescriptor();

var descriptor2 = new ActionDescriptor();

var reference = new ActionReference();

reference.putProperty(cTID('Prpr'), cTID('time'));

reference.putClass(sTID("timeline"));

descriptor.putReference(cTID('null'), reference);

descriptor2.putInteger(sTID("seconds"), seconds);

descriptor2.putInteger(sTID("frame"), frame);

descriptor2.putDouble(sTID("frameRate"), frameRate);

descriptor.putObject(cTID('T   '), sTID("timecode"), descriptor2);

executeAction(cTID('setd'), descriptor,  DialogModes.NO);

}

setVideo(4, 29, 30);

I ask for you to show me what was recorded for the last few action steps options.  I did not ask for a mp4 or how you recorded the  last step.  I told you Action steps record hard coded settings.  What settings were recorder into you action. Would they be valid for the document you play the action on or use a script equipment to one of your action's hard coded action step?  I'm trying to help you why not cooperate and reply with what I ask you to provide.  To me it looks like seconds 4 frame 29 rate 30 was recorded is that correct.

In your mp4 it looks like you recorded. It look like you have a video open in Photoshop and had recorded sometime in the past an action named set in Adobe default action set.   The action has one step "Set Time of timeline" the action step is not expanded and you did not show how the step was recorded.  You may have played the action with the open document  video timeline created  and you may have move a video timeline time slider but that seems to be moved to the 5th second,  You may also be using some third party extension to convert the action to a script or you may have used  X;s xtools kit to do that and  then third party extension  you added action  converted to a script in as a button.  You say the nothing happens when you use the set script.  Have you tried using the script from menu File>Scripts>script name or Browse to where the converted action is stored as a jsx file.   If the slider needed to be moved first did you doe the steps need in the document before tried using the script?  It look like values 4, 29 and 30 were recorded into the action so they are also in the script for no logic was added the change these values. Thes values will mnots likel not be valid fot all video timemines.