Having viewed hundreds of siren videos over the twelve years that I have been active on this board, I thought that I'd give a few suggestions to those of you who submit Youtube videos to make them more enjoyable. These are general recommendations not targeted to anyone specifically.
1. Avoid talking while the siren sounds. Resist the temptation to yell something when the siren starts, and don't bring your friends with you unless they can keep silent. You don't need to remind us that the siren is starting when we can plainly hear it.
2. Don't force viewers to watch two minutes of movie-style credits before a thirty-second siren clip. Your film will never make it big in Hollywood or online, so just get to the point and spare the big production stuff. All we want to hear is the siren.
3. If you have background music, end it before the siren starts. If you're filming from a moving car, turn off the stereo before you enter the area where the siren can be heard.
4. Try to locate your camera some distance from the siren so that the sound does not come out distorted. This also takes advantage of local acoustics and reverberation. If it is a windy day, try filming from inside a car with a window rolled down to cut down on wind or ambient noise. Park the car so that the wind blows perpendicular to the open window.
5. If you have video editing software, cut out most of the blank time before the siren sounds. Ten or twenty seconds of waiting is fine for most viewers, but three minutes is not. When the siren shuts off, try to get most of the wind-down, but remember that because it takes some sirens several minutes before the rotor stops moving, most people aren't willing to wait for it to stop.
6. I know that not everyone can afford high-end cameras and equipment, but if a basic tripod is out of your budget, at least place your camera on a flat surface rather than holding it in your hand. When the siren starts suddenly, the picture won't jump when you do.
I hope that these suggestions will be useful for you.