DOC added some explanation to video page

Author: amueller

doc/presentations.rst

@@ -8,10 +8,14 @@ Videos
 - `Introduction to scikit-learn
   <http://videolectures.net/icml2010_varaquaux_scik/>`_ by `Gael Varoquaux`_ at
   ICML 2010
+    A three minute video from a very early stage of the scikit, explaining the
+    basic idea and approach we are following.
 
-- Extensive four part `Introduction to machine learning with scikit
+- `Introduction to machine learning with scikit
   learn <http://archive.org/search.php?query=scikit-learn>`_ by
   `Gael Varoquaux`_ at SciPy 2011
+    An extensive tutorial, consisting of four 90 minute sessions. The tutorial covers basics of machine learning,
+    many algorithms and how to apply them using scikit-learn.
 
 - `Statistical Learning for Text Classification with scikit-learn and NLTK
   <http://blip.tv/pycon-us-videos-2009-2010-2011/pycon-2011-statistical-machine-learning-for-text-classification-with-scikit-learn-4898362>`_
@@ -21,10 +25,13 @@ Videos
 - `Statistical Learning for Text Classification with scikit-learn and NLTK
   <http://blip.tv/pycon-us-videos-2009-2010-2011/pycon-2011-statistical-machine-learning-for-text-classification-with-scikit-learn-4898362>`_
   by `Olivier Grisel`_ at PyCon 2012
+    Thirty minute introduction to text classification. Explains how to use NLTK and scikit-learn to solve real-world text classification
+    tasks and compares against cloud-based solutions.
 
 
 - `scikit-learn - Machine Learning in Python <http://marakana.com/s/scikit-learn_machine_learning_in_python,1152/index.html>`_
   by `Jake Vanderplas`_ at the 2012 PyData workshop at Google
+    Interactive demonstration of some scikit-learn features. 75 minutes.
 
 .. _Gael Varoquaux: http://gael-varoquaux.info
 .. _Jake Vanderplas: http://www.astro.washington.edu/users/vanderplas/