how to capture the data using DMV's in sql server 2008 r2?
The clue is in the name, DMVs are Dynamic Management Views. The data they return is dynamic and will be the latest values available to the system, so they will be constantly updating themselves. So the best you could do is to sample them at a set interval and then try to extrapolate the intermdiate values if you really need them

Some of the DMVs do capture cumulative statistics (sys.dm_exec_query_stats for example, captures cumulative stats about queries). But they don't offer the sort of access you might be looking for at the individual query level.

Your other option may be to use Extended Events ( http://msdn.microsoft.com/en-us/library/bb630354%28v=sql.105%29.aspx ) to capture the queries that the devs are submitting. Pinal Dave provides a nice example of capturing queries - http://blog.sqlauthority.com/2010/03/29/sql-server-introduction-to-extended-events-finding-long-running-queries/ - his is based on capturing long running queries, but you could easily reduce the time critreia for capture, or remove it completely in favour of a login match or applictaion match as required.