Several news sites now carrying reports about several different fisherman reporting a 'low flying' aircraft moving very fast just off the Malay coast. One fisherman saying that the lights were about the 'size of coconuts' which is why he knew it was very low. Apparently these reports are why the search area has now been expanded to include areas of land.
It would appear that they really have no idea what general area this aircraft went down in.
If indeed this was the aircraft flying low back towards Malaysia then it must be a deliberate act to turn around, descend and then crash the aircraft...... of course these reports could be completely false as eye witnesses are historically very very bad sources when it comes to aircraft accidents.