Here's my long-winded input...
I think you want to give your audience options, but not overwhelm them with difficult choices or burden them with redundancies. What I've learned from my career in interactive entertainment is that MOST audiences really don't like to interact! If you want to appease the masses, as the author/creator/director you need to provide simple, unobtrusive choices for how your audience consumes content and let people "dig deeper" if they want.
How does all that relate to a trip report and mixing video/pics and replacing audio in video? Well, ultimately remember you are telling a story that should have a beginning, middle and an end. You can frame that story to different people in different ways for varying levels of engagement, but what you do NOT want to do is lose the impact of the primary story with:
a) another story
b) too much detail for a specific audience
c) telling the same story again within the story.
So... on the trip report, I'd include clear links right up front if users can consume the story in different ways. For instance I might immediately link to the full-length video or the "daily journal" so people who prefer those options can jump to them. (Each should have their own beginning, middle and end.)
For the audience that doesn't click away, I'd create the standard written overview report with opportunities for users to dig deeper if they want. Thus, you can intermix video, but it should be short and help illustrate a specific point -- just like a photo would at that moment. You don't want the viewer to lose the train of thought of the primary story. Since in this context, embedded/linked video within a story should be really short, you shouldn't have to worry too much about adding music the same way you'd need to for a longer video or a teaser video. This is similar to how photos can be clickable to see more pixel detail and/or offer a more detailed caption that you don't want to slow down your casual reader (ie "This photo was time-lapse taken over the course or 2hrs" or "The trail here winds up through this boulder field, the best route is on the far left.")
In contrast to "more detail" links to pics/video, I try to resist embedding links during the report to OTHER reports. This is because it forces your audience to make a decision they may not be comfortable with at that moment. Imagine.... I'm telling you are really good story and before I finish, I give you the chance to hear another potentially good story. Darn -- what do I do?! I prefer to have all "related info" links at the end (eg "Read about my 2009 epic in the same canyon.")
I also try to avoid being redundant -- such as linking to a picture that's basically the same size/framing or with a caption similar to the report description. I'd also avoid a short video piece which basically shows the same view.. just in motion. This becomes tedious for users and they will end up not clicking on the embedded links for detail.
So... ideally in the end you've told your story to appeal to several different audiences:
Super-casual (Facebook) -- "Look at the pretty picture from a hike... oh no, my Farmville crops are dying."
Casual Enthusiast -- "Cool, let me scan this trip report. I'll scroll past most of it and stop on a few photos I like."
Video Enthusiast -- "Great, there's a video report, I'll watch that."
True Enthusiast -- "Awesome report, I read every word and clicked most items to learn as much as possible."
Hardcore Fan -- "Incredible, this and all the related links help with my upcoming trip -- especially the walk-though of the entire canyon!"
Of course all takes an incredible amount of work, so I commend you if you can pull it off! I still have tons of video (and pics) that I've never incorporated the way I'd like to. Someday... or maybe I'll just do another hike instead!
