Grab the end of the clip, and holding the [Ctrl] key down, drag the clip as far as you want. This will stretch it out. It will now play back in slow motion.
If you mean your original clip, when you place it on the timeline, it is just stretching that clip for that time, your original clip that you got from your media library is not changed.
No I mean just in the timeline. I have played around with changing speeds on some events but I could not tell if I put the clip back to normal in the timeline.
On the event properties/general tab, set the playback rate back to 1.0 to return to normal speed... however, if "loop" is checked, the event will begin to play over again. Whether or not loop is checked, the event will remain as long as it was but can be split at the start of the loop, with the remaining portion discarded....
There is probably an easier way to do it, but I believe the above works...
This is only useful if you know about where the original end point is ... when you change the speed the clip will have a jagged "Charlie Brown shirt" line through it. When you get close to the orignal speed again the end of the clip will snap into position and this jagged line will disappear. If you're a little bit careful it's very easy to snap it back to 100% speed.
Same thing in reverse. Hold down ctrl and drag the edge back to where it started. When you're there, the zig-zag line in the clip event will disappear and you'll snap into place.