Cylon birds and other random things

While walking in the hutong neighborhoods, I heard a strange mechanical whistling sound that reminded me of a jet or a Cylon raider. I wondered if someone was flying a remote controlled plane or something. Looking up, I saw a small flock of pigeons or doves flying around, and as I watched them and walked around, it became quite clear from the Doppler effect that the sound was coming from the birds. I've never heard anything like it. I couldn't catch them for a still photo since I was down in an alley, only managed this awful shot:

Luckily, I did manage to catch them on video and you can hear the odd sound in the recording. Can anyone out there tell me what kind of bird this is and why they make the sound? I did search Google, but all I came up with was the whistling sound made by the wings of doves when they take off, which is nothing like the sound from these birds, which was constant while they were flying around.

Speaking of birds, this is obviously not made by the same kind of birds, but I thought it made a pretty winter photo.

Snow graffiti, Chinese style:

Perhaps it is because I'm from an eqrthquake prone place that I found these almost-touching buildings so disturbing:

In the feminine hygiene section of the supermarket, I found this odd product.

"Men's feminine nursing wipes" for "dedicated men"... say what? (O.o)