A new 30-second trailer for the CW’s Flash TV series, which is based on the DC Comics character and which debuts October 7th, demonstrates several different ways in which the producers of the new show plan to depict Barry Allen’s super-speed including using slow-motion so that the viewers can actually see what The Flash is doing.  The visual effects certainly appear to be quite effective in this promotional setting.
 
The CW is rebroadcasting the two episodes of Arrow that introduced the Barry Allen/Flash character back-to-back on October 1st, which should provide a great lead to The Flash series, which debuts the next week (see "'The Flash,' 'Arrow' Launches Set").  The new Flash TV show is set in the same “world” as the Arrow series, which is based on DC Comics’ Green Arrow.