From Bate, Tricco & Price (2013), "Collapse of a molecular cloud core to stellar densities: stellar core and outflow formation in radiation magnetohydrodynamics simulations", published in Monthly Notices of the Royal Astronomical Society.
The movie shows a computer simulation of a spherical rotating ball of gas, collapsing under its own gravity all the way from a density of 10^-21 times the density of water to form a star, with a mean density around that of water. The gravitational collapse stalls at two points - the `first core', where the gas first traps radiation. This temporary core then collapses again to form the `second core' which is the proto-star. At each of these stall phases the wind-up of magnetic fields leads to the launch of outflows or `jets' of gas. We observe these in every star forming region in the Milky Way, and this calculation helps us to understand their origin in the star formation process.
For the full paper and images, see: users.monash.edu.au/~dprice/pubs/stellar-jet/