Ivan Laptev's code on Space-time interest points (STIP) detection can be downloaded
here. To run it on Ubuntu 12.04, there are several dependencies you need to install.
First you need to install OpenCV. As the newer version of OpenCV's library names are changed and the code is compiled with the older version of the library, you need to make symbolic links that point from the old library names to the new library names. The
stackoverflow post lists all the symbolic links you need to make.
In order to make video reading work with OpenCV, you need to compile OpenCV with libgtk2.0-dev and pkg-config installed. Also you need libgstreamer0.10-dev and libgstreamer0.10-vaapi-dev. The libgstreamer0.10-vaapi-dev provides the headers such as gst/video/video.h which is required in compiling OpenCV.