Youtube is easy to upload on. Go click "Upload" on the right of the header and log in using you member name and password you created your account with.
You'll go to a page where you can enter a title and description for your video. Put your title and description in then put some tags (siren fire truck emergency) and whatever category your video is. Afterwords, you'll go to a second page where you put the video file on and just let it upload.
I haven't tested uploading video on a dialup but I'm sure it will take a while.
Back on topic; I have a flashlight siren made in Hong Kong as well that orginally belonged to my aunt. Does it look like this one ?