your flash doesnt work if you embed it with allowscriptaccess="never" allownetworking="none"
there's something strange you're doing in the flash that should not be needed in a simple flash loop. maybe you added some weir preloader?>>3324338
export your movie as jpg images and import to the timeline. you can use jpgs in flash>>3324346
adobe has been bad for flash since they bought it. they just refused to make it possible to embed h264 movies on the timeline and after they fuck up flash enough they just abandon it. flash can handle it, just not embed it in the timeline. curse adobe.
worst screwup is that flash can render using graphics cards but you need to embed it with a special attribute so it never took off. once upon a time you could export swf games directly from the unity engine but due to adobe's poor management they lost that. and adobe actually made a flash store (like apple's app store) but 5 years too late so nobody used it and they took it down a year later. so bad..