That kind of artwork is always done better in Illustrator. If you have to stick with Photoshop, make several images. For the first one take the original large image and save a copy that is no larger than 3X the main comp size. Now go back to the original image and crop it so that it includes about the same area as your smaller image would include when it is at 100% scale and framed up properly so that you can cut from the small master to the cropped master and not see the cut. Repeat as many times as necessary until you have an image that is set to the final detail area you want to show in the comp at 100% scale. This is about the only way you are going to be able to efficiently work with this kind of a project.
Another consideration - Line thickness. If your original image is 10 X the width of the video you are trying to create (main comp size) then a line that is less than 10 pixels thick in the original artwork will almost completely disappear in the comp if you show the entire image. If the line is going to be moving then it must be at least 20, or even better 30 pixels wide in the original artwork if you are going to keep it from flickering as it moves when you are looking at the entire image. These are the design challenges you face when trying to move in on a large illustration.
I usually solve the problem by designing the large artwork that needs to be seen at full screen at about 2X comp size to let me do a little movement, then create separate overlays for the other text and graphics at the appropriate size for their hero positions. Then I use transitions to bring the detail artwork into view. It takes a little planning but produces much better and more watchable results in the long run.
I hope these suggestions help.
