This video is about a marsh warbler singing in Sweden.
From the Flamborough Bird Observatory in England:
Tuesday, August 5th, 2014
The Observatory is pleased to announce that a pair of Marsh Warblers took up territory in late May. The pair stayed and eventually were seen carrying food and extracting faecal sacs from a presumed nesting spot. Eventually at least one juvenile was seen to have fledged, although it was strongly suspected that there were more.
The site was vulnerable to disturbance and unable to be monitored. In consultation with RSPB staff the decision was made to keep disturbance to a minimum.
Marsh warblers are really rare in Britain.
When I was at Bempton Cliffs, not far from Flamborough head, on 5 July 2011, I was surprised to see a relative of the marsh marbler there: a sedge warbler. A lot more common in England than marsh warblers, but still surprising to see it near coastal cliffs, not in a marsh.