I use the process that Timo suggests a lot. I load a large video on an audio track with an eSession or eArrangement plug-in and then look for the samples I want to use. I set the in/out points of the clip to cut out the sample and then drag the clip into the eConvert with ‘Crop to Clip Start/End’ enabled.
Another approach I really like:
I cut out a scene of max 60 seconds from a larger video using the process described above and then drag the video into the eSampler. In the eSampler I cut samples from the scene using the File Region Editor and then convert them to Hap with the File Region Editor.
While the eSampler is converting you can continue working. The eSampler will automatically replace the large scene with the Hap sample when finished. Very convenient! Before I convert to Hap (and the scene will be replaced) I usually duplicate the eSampler with the scene, so I can use that to cut the next sample.
Read more about the File Region Editor here: