As I previously blogged, Premiere CC’s [Undo] does not undo media-replacement in Project pane. This was discussed on an Adobe Premiere forum thread. As part of that discussion, the “can’t please everyone” principle was apparent: one view was in favor of that Undo behaviour, another was against it.
Maybe-ideally, both viewpoints would be satisfied if, say, the History window would have a column of checkboxes for “Locked”, meaning all changes are recorded but [Undo] will skip over those having a check-mark (when they could also be greyed-out). The “Media Replace” action could have a default of “Locked”, so it behaves as at present, for those people who like it that way.
I wish such a change-lock feature existed in any case, e.g. if I have made a string of color corrections etc. to various clips on timeline and then afterwards realise there is some “obscure show-stopping issue most productively solved by undo-ing”. One could lock the simple color correction effects etc. prior to undoing as far back as necessary to fix the issue (such as some media link or interpretation or sync issue). I realise it is possible to achieve this by work-arounds, e.g. save to a Project copy then Import that copy and copy/paste attributes each effect across, or one could save Effect Presets and re-apply these after undoing. But such workaround would be cumbersome if there were a number of different effect tweaks on a variety of clips, and one would have to remember/note which clips these were (or else go through all clips). And then there are non-effect changes, like “ripple trim” cut-timing tweaks.
It would also be helpful if the History-window said more specific things than just “Apply Effect” (like which effect) and if the History-window automatically came to the fore when applying an Undo. Those things together would reduce the likelihood of unintended undo’s of any kind.