(Copy pasting from the hi-score thead)
I uploaded a video of myself no-missing the first section of stage 5. That part is a big wall for everyone and I guess any help is welcome.
http://www.megaupload.com/?d=FLJXE9LN
The best approach, imo, is to destroy all enemies quickly before they overwhelm you. So you need to memorize when and which enemies appear at all times.
The order of appearance of those small drones is:
1) Bottom left corner (8 drones)
2) Bottom right corner (8 drones)
3) Upper left corner (4 drones)
4) Upper right corner (4 drones)
5) Upper left corner (8 drones)
6) Upper right corner (8 drones)
7) Repeat steps 1 to 6
8 ) Midboss
The most dangerous drone waves are the ones that come from the bottom, but the video shows how to deal with them: make it so that your napalm hit all incoming enemies before they shoot at you.
Also, a big red ship appears with every drone wave. What you need to know about them:
a) If you destroy one of those plates covering its guns, that side won't shoot anymore
b) If you destroy both plates, the ship will self destruct
Watch the video for reference and practice, and you should get past that part.