Added detail about not using timings for precision 📝

recipe/0489-multimedia-canvas/index.md

@@ -19,6 +19,8 @@ This recipe pulls together techniques and structures described in other recipes,
 
 While other recipes have discussed [simple textual annotations][0266], this recipe changes the motivation for its textual annotations to `painting` to include the text directly and visibly on the Canvas. Each of the annotations in this recipe is bound both by its placement on the Canvas and by its time of visibility.
 
+When using timing for showing and hiding resources on a Canvas, a high degree of precision is not likely to be achieved for all people viewing the Canvas. Resources may load slowly for many reasons, including on the IIIF image server side, for network traffic reasons, or from customizations in a person's browser. Except in a very predictable environment, timing should be considered approximate
+
 ## Restrictions
 
 No restrictions known.
@@ -27,7 +29,7 @@ No restrictions known.
 
 In this example, a still image, a video, and plaintext annotations are combined on a single Canvas to simulate a classroom assignment designed to introduce students to image study and notetaking in a compressed period of time. Note that this example contains material pedagogical design flaws and is not to be used as is for a classroom assignment.
 
-A person using a viewer that supports this recipe is presented first with the instruction to "Press Play", added using a time-bound plaintext annotation. After pressing play, additional instructions appear, also created using a time-bound plaintext annotation. When the time elapses on this annotation, the person is presented with a clock video overlaid on top of a still image. In the hypothetical assignment, a student would follow the instructions and take notes on the still image while the clock counts up the time allotted. After 30 seconds passes, the still image and clock video disappear, replaced by text instructions to close the browser.
+A person using a viewer that supports this recipe is presented first with the instruction to "Press Play", added using a time-bound plaintext annotation. After pressing play, additional instructions appear, also created using a time-bound plaintext annotation. When the time elapses on this annotation, the person is presented with a clock video overlaid on top of a still image. In the hypothetical assignment, a student would follow the instructions and take notes on the still image while the clock counts up the time allotted. After 30 seconds passes, the still image and clock video disappear, replaced by text instructions to close the browser. (These final instructions stay visible for approximately 2-1/2 minutes to avoid an immediate return to the initial instructions.)
 
 [Theseus Viewer temporary link](https://theseus-viewer.netlify.app/?iiif-content=http://localhost:4000//recipe/0489-multimedia-canvas/manifest.json)