Why doesn't add to selection and scale ever work in quicktime.

I can not get songs to end at the same time the video does.

What codecs are involved? What is your work vlow? (E.g., which codec is being "added" to which codec?)

I have no idea what codecs are. I thought you could get quick time to change the length of the song to match the length of the video but I guess It's not as simple as that.

It may not be. Basically, a video consists data which has been encoded/compressed using particular audio and/or video codecs that can then be wrapped or placed in one or more types of file containers. Some codecs are "Playback Only" in QT 7. Others are "Coversion Compatible" (playback and conversion compatible with the QT 7 Pro player) while another group may be "Fully Compatible" which means they can played, converted, and editied by the QT 7 Pro player. Thus, if your are adding a non-editable data stream to an editable or non-editable data stream, the file timing probably cannot be edited/adjusted but if you add them in the reverse order may be edit/ajustable. Whereas, a defualt QT 7 format like MPEG-4/AVC video with AAC audio wrapped in an MOV, MP4, or M4V file container can normally be "added & scaled" in either direction. That is why I asked about the codecs and which was being added to which. In most cases, when posting question here, you should include the file extension, audio and/or video codecs, and the particular player or app you tring to use to play, edit, or convert the data in since different data is sometimes handled/treated differently in different containers and/or by different apps.