The problem is that that's not true anymore either. Many intros are equally "long full effort" as your average demo. Intro simply means "demo with a size limit", these days (and by "these days" i mean "the last 15 years")
From http://tomaes.32x.de/text/faq.php:
A wild demo can be pretty much everything. Some possibilities:
- It's any kind of film, usually available as divx/avi file
(music videos, shorts, comedies, trash, prerendered animations...)
- It's a demo that requires very rare/strange hardware to run
(c64 with SCPUs, for example)
- It's a demo that simply does not fit in any other competition (and the
applying rules) of a given demoparty.
- Sometimes, live performances count as 'wild' demos too. ;)
However, in most cases, it IS a short movie (clip), either tradionally filmed
or CG/animated.https://www.youtube.com/watch?v=KTjnt_WSJu8
Nowadays megademos might be put into the wild demo compo, but from what i know parties put length restrictions on those as well. The primary purpose of wild demo compos however is to allow platforms that do not compare well with the classic demo platforms, such as the various ARM mini computers, game consoles or really old computers.
http://www.pouet.net/prod.php?which=1331 http://www.pouet.net/prod.php?which=3119 http://www.pouet.net/prod.php?which=3242 http://www.pouet.net/prod.php?which=3972